Fix RemoteClusterSecurityFcActionAuthorizationIT testIndicesPrivilegesAreEnforcedForCcrRestoreSessionActions to wait for references to be cleared (fixes elastic#127782) (elastic#127888)

Author: mosche

muted-tests.yml

@@ -432,9 +432,6 @@ tests:
 - class: org.elasticsearch.backwards.MixedClusterClientYamlTestSuiteIT
   method: test {p0=search/350_point_in_time/point-in-time with index filter}
   issue: https://github.com/elastic/elasticsearch/issues/127741
-- class: org.elasticsearch.xpack.remotecluster.RemoteClusterSecurityFcActionAuthorizationIT
-  method: testIndicesPrivilegesAreEnforcedForCcrRestoreSessionActions
-  issue: https://github.com/elastic/elasticsearch/issues/127782
 - class: org.elasticsearch.compute.aggregation.FilteredGroupingAggregatorFunctionTests
   method: testSimpleCircuitBreaking
   issue: https://github.com/elastic/elasticsearch/issues/127833

x-pack/plugin/security/qa/multi-cluster/src/javaRestTest/java/org/elasticsearch/xpack/remotecluster/RemoteClusterSecurityFcActionAuthorizationIT.java

@@ -281,7 +281,7 @@ public void testIndicesPrivilegesAreEnforcedForCcrRestoreSessionActions() throws
                 GetCcrRestoreFileChunkAction.REMOTE_TYPE,
                 new GetCcrRestoreFileChunkRequest(response2.getNode(), sessionUUID2, leaderIndex2FileName, 1, shardId2)
             );
-            assertFalse(getChunkResponse.getChunk().hasReferences());
+            assertBusy(() -> assertFalse(getChunkResponse.getChunk().hasReferences()));
 
             // Clear restore session fails if index is unauthorized
             final var e4 = expectThrows(