Fix testStartCloneWithSuccessfulShardSnapshotPendingFinalization (#63966)

We have to wait for no more operations here not for `1`. This mostly worked
because the test thread would add the listener quickly enough so that it sees the
state where either the snapshot or clone but not both have already finished
but randomly the test thread would be slow and time out on a state without snaphots in it.

server/src/internalClusterTest/java/org/elasticsearch/snapshots/CloneSnapshotIT.java

@@ -562,7 +562,7 @@ public class CloneSnapshotIT extends AbstractSnapshotIntegTestCase {
         } finally {
             unblockNode(repoName, masterName);
         }
-        awaitNumberOfSnapshotsInProgress(1);
+        awaitNoMoreRunningOperations();
 
         awaitMasterFinishRepoOperations();