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

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

@@ -2218,8 +2218,12 @@ public class SharedClusterSnapshotRestoreIT extends AbstractSnapshotIntegTestCas
                         .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 class SharedClusterSnapshotRestoreIT extends AbstractSnapshotIntegTestCas
         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 @@ public class SharedClusterSnapshotRestoreIT extends AbstractSnapshotIntegTestCas
         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");