[CI] AzureSearchableSnapshotsIT testSourceOnlyRepository failing

[pugnascotia]

Also failed on 7.x - https://gradle-enterprise.elastic.co/s/xn3lc6t7eqt46

Build scan:
https://gradle-enterprise.elastic.co/s/ojr27vpb2o2xi/tests/:x-pack:plugin:searchable-snapshots:qa:azure:integTest/org.elasticsearch.xpack.searchablesnapshots.AzureSearchableSnapshotsIT/testSourceOnlyRepository

Reproduction line:
./gradlew ':x-pack:plugin:searchable-snapshots:qa:azure:integTest' --tests "org.elasticsearch.xpack.searchablesnapshots.AzureSearchableSnapshotsIT.testSourceOnlyRepository" -Dtests.seed=96BD0E2B8F3C43C7 -Dtests.locale=cs -Dtests.timezone=Asia/Atyrau -Druntime.java=11

Applicable branches:
master, 7.x

Reproduces locally?:
Didn't try

Failure history:
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.searchablesnapshots.AzureSearchableSnapshotsIT&tests.test=testSourceOnlyRepository

Failure excerpt:

org.elasticsearch.client.ResponseException: method [POST], host [http://127.0.0.1:42243], URI [/rrxlzjtise/_search?ignore_throttled=false], status line [HTTP/1.1 500 Internal Server Error]
{"error":{"root_cause":[{"type":"unsupported_operation_exception","reason":"_source only indices can't be searched or filtered"}],"type":"search_phase_execution_exception","reason":"all shards failed","phase":"can_match","grouped":true,"failed_shards":[{"shard":0,"index":"rrxlzjtise","node":"IdQg-ya8T9KsO1c1xpzupA","reason":{"type":"unsupported_operation_exception","reason":"_source only indices can't be searched or filtered"}}],"caused_by":{"type":"unsupported_operation_exception","reason":"_source only indices can't be searched or filtered","caused_by":{"type":"unsupported_operation_exception","reason":"_source only indices can't be searched or filtered"}}},"status":500}

  at __randomizedtesting.SeedInfo.seed([96BD0E2B8F3C43C7:5F228075D2D66DF6]:0)
  at org.elasticsearch.client.RestClient.convertResponse(RestClient.java:330)
  at org.elasticsearch.client.RestClient.performRequest(RestClient.java:296)
  at org.elasticsearch.client.RestClient.performRequest(RestClient.java:270)
  at org.elasticsearch.xpack.searchablesnapshots.AbstractSearchableSnapshotsRestTestCase.search(AbstractSearchableSnapshotsRestTestCase.java:483)
  at org.elasticsearch.xpack.searchablesnapshots.AbstractSearchableSnapshotsRestTestCase.lambda$testSourceOnlyRepository$2(AbstractSearchableSnapshotsRestTestCase.java:212)
  at org.elasticsearch.xpack.searchablesnapshots.AbstractSearchableSnapshotsRestTestCase.runSearchableSnapshotsTest(AbstractSearchableSnapshotsRestTestCase.java:164)
  at org.elasticsearch.xpack.searchablesnapshots.AbstractSearchableSnapshotsRestTestCase.testSourceOnlyRepository(AbstractSearchableSnapshotsRestTestCase.java:206)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:566)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:49)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:45)
  at org.apache.lucene.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:48)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:64)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:824)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:475)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:45)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:41)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:47)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:64)
  at org.apache.lucene.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:54)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:831)
  at java.lang.Thread.run(Thread.java:834)

[elasticmachine]

Pinging @elastic/es-distributed (Team:Distributed)

[fcofdez]

I think this is related to #76100