Fix testSnapshotRelocatingPrimary to Actually Run Relocations (#46594)

* Fix testSnapshotRelocatingPrimary to Actually Run Relocations

Without replicas we won't actually get any relocations
going when removing the node constraints in this test.
Adjusted the code to force relocations by forbidding
nodes that hold primaries instead.
Also, fixed the timeouts and asserted that we actually
get relocations.

Fixes #46276

Author: original-brownbear

server/src/test/java/org/elasticsearch/snapshots/SharedClusterSnapshotRestoreIT.java

@@ -2218,8 +2218,12 @@ public void testSnapshotRelocatingPrimary() throws Exception {
                         .put("compress", randomBoolean())
                         .put("chunk_size", randomIntBetween(100, 1000), ByteSizeUnit.BYTES)));
 
-        // Create index on 1 nodes and make sure each node has a primary by setting no replicas
-        assertAcked(prepareCreate("test-idx", 1, Settings.builder().put("number_of_replicas", 0)));
+        // Create index on two nodes and make sure each node has a primary by setting no replicas
+        assertAcked(prepareCreate("test-idx", 2, Settings.builder()
+            .put(SETTING_NUMBER_OF_REPLICAS, 0)
+            .put(SETTING_NUMBER_OF_SHARDS, between(2, 10))));
+
+        ensureGreen("test-idx");
 
         logger.info("--> indexing some data");
         for (int i = 0; i < 100; i++) {
@@ -2229,11 +2233,13 @@ public void testSnapshotRelocatingPrimary() throws Exception {
         assertThat(client.prepareSearch("test-idx").setSize(0).get().getHits().getTotalHits().value, equalTo(100L));
 
         logger.info("--> start relocations");
-        allowNodes("test-idx", internalCluster().numDataNodes());
+        allowNodes("test-idx", 1);
 
         logger.info("--> wait for relocations to start");
 
-        waitForRelocationsToStart("test-idx", TimeValue.timeValueMillis(300));
+        assertBusy(() -> assertThat(
+            client().admin().cluster().prepareHealth("test-idx").execute().actionGet().getRelocatingShards(), greaterThan(0)),
+            1L, TimeUnit.MINUTES);
 
         logger.info("--> snapshot");
         client.admin().cluster().prepareCreateSnapshot("test-repo", "test-snap").setWaitForCompletion(false).setIndices("test-idx").get();
@@ -2806,11 +2812,6 @@ private boolean waitForIndex(final String index, TimeValue timeout) throws Inter
         return awaitBusy(() -> indexExists(index), timeout.millis(), TimeUnit.MILLISECONDS);
     }
 
-    private boolean waitForRelocationsToStart(final String index, TimeValue timeout) throws InterruptedException {
-        return awaitBusy(() -> client().admin().cluster().prepareHealth(index).execute().actionGet().getRelocatingShards() > 0,
-            timeout.millis(), TimeUnit.MILLISECONDS);
-    }
-
     public void testSnapshotName() throws Exception {
         disableRepoConsistencyCheck("This test does not create any data in the repository");