[ML] 8.x ML full cluster restart tests can run against old 7.x

There was a mistake in elastic#80876, where the assumption was made
that for 8.x versions the old cluster would understand composable
templates. This is true for rolling upgrade tests but not full
cluster restart tests. This commit fixes that.

Author: droberts195

x-pack/qa/full-cluster-restart/src/test/java/org/elasticsearch/xpack/restart/MlConfigIndexMappingsFullClusterRestartIT.java

@@ -43,7 +43,11 @@ protected Settings restClientSettings() {
     public void waitForMlTemplates() throws Exception {
         // We shouldn't wait for ML templates during the upgrade - production won't
         if (isRunningAgainstOldCluster()) {
-            XPackRestTestHelper.waitForTemplates(client(), XPackRestTestConstants.ML_POST_V7120_TEMPLATES, true);
+            XPackRestTestHelper.waitForTemplates(
+                client(),
+                XPackRestTestConstants.ML_POST_V7120_TEMPLATES,
+                getOldClusterVersion().onOrAfter(Version.V_7_8_0)
+            );
         }
     }
 

x-pack/qa/full-cluster-restart/src/test/java/org/elasticsearch/xpack/restart/MlHiddenIndicesFullClusterRestartIT.java

@@ -58,7 +58,11 @@ protected Settings restClientSettings() {
     public void waitForMlTemplates() throws Exception {
         // We shouldn't wait for ML templates during the upgrade - production won't
         if (isRunningAgainstOldCluster()) {
-            XPackRestTestHelper.waitForTemplates(client(), XPackRestTestConstants.ML_POST_V7120_TEMPLATES, true);
+            XPackRestTestHelper.waitForTemplates(
+                client(),
+                XPackRestTestConstants.ML_POST_V7120_TEMPLATES,
+                getOldClusterVersion().onOrAfter(Version.V_7_8_0)
+            );
         }
     }
 

x-pack/qa/full-cluster-restart/src/test/java/org/elasticsearch/xpack/restart/MlMigrationFullClusterRestartIT.java

@@ -6,6 +6,7 @@
  */
 package org.elasticsearch.xpack.restart;
 
+import org.elasticsearch.Version;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
 import org.elasticsearch.common.Strings;
@@ -51,7 +52,11 @@ protected Settings restClientSettings() {
     public void waitForMlTemplates() throws Exception {
         // We shouldn't wait for ML templates during the upgrade - production won't
         if (isRunningAgainstOldCluster()) {
-            XPackRestTestHelper.waitForTemplates(client(), XPackRestTestConstants.ML_POST_V7120_TEMPLATES, true);
+            XPackRestTestHelper.waitForTemplates(
+                client(),
+                XPackRestTestConstants.ML_POST_V7120_TEMPLATES,
+                getOldClusterVersion().onOrAfter(Version.V_7_8_0)
+            );
         }
     }