Fix success countdown latch in UT & remove redundant condition

Signed-off-by: Ashish Singh <[email protected]>

server/src/test/java/org/opensearch/index/shard/RemoteStoreRefreshListenerTests.java

@@ -217,7 +217,8 @@ public void testRefreshSuccessOnFirstAttempt() throws Exception {
         // We spy on IndexShard.getReplicationTracker() to validate that we have tried running remote time as per the expectation.
         CountDownLatch refreshCountLatch = new CountDownLatch(succeedOnAttempt);
         // We spy on IndexShard.getEngine() to validate that we have successfully hit the terminal code for ascertaining successful upload.
-        CountDownLatch successLatch = new CountDownLatch(2);
+        // Value has been set as 3 as during a successful upload IndexShard.getEngine() is hit thrice and with mockito we are counting down
+        CountDownLatch successLatch = new CountDownLatch(3);
         mockIndexShardWithRetryAndScheduleRefresh(succeedOnAttempt, refreshCountLatch, successLatch);
         assertBusy(() -> assertEquals(0, refreshCountLatch.getCount()));
         assertBusy(() -> assertEquals(0, successLatch.getCount()));
@@ -302,7 +303,6 @@ private void mockIndexShardWithRetryAndScheduleRefresh(
             return indexShard.getSegmentInfosSnapshot();
         }).when(shard).getSegmentInfosSnapshot();
 
-        when(shard.getEngine()).thenReturn(indexShard.getEngine());
         doAnswer(invocation -> {
             successLatch.countDown();
             return indexShard.getEngine();