Remove assertion in testDocStats on deletedDocs counter (elastic#32914)

testDocStats test is flaky and sometimes it's failing on jenkins and
failure is not reproducible locally. The reason for this failure is in
timing. If the number of deleted documents is greater than 33% of inserted
documents, Lucene will schedule segments to merge if TieredMergePolicy is
used (it's not the case for LogMergePolicy, but ES is only using
TieredMergePolicy). If this merge is performed before stats are
retrieved - we will get 0 for "deleted" counter.
So basically this counter could be either 0 or numOfDeletedDocs at this point,
but this is the too loose assertion and we decided to remove it at all.
Closes elastic#32766

server/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java

@@ -2389,8 +2389,7 @@ public void testRecoverFromLocalShard() throws IOException {
         closeShards(sourceShard, targetShard);
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/32766")
-    public void testDocStats() throws IOException {
+    public void testDocStats() throws IOException, InterruptedException {
         IndexShard indexShard = null;
         try {
             indexShard = newStartedShard();
@@ -2439,8 +2438,6 @@ public void testDocStats() throws IOException {
                     assertTrue(searcher.reader().numDocs() <= docStats.getCount());
                 }
                 assertThat(docStats.getCount(), equalTo(numDocs));
-                // Lucene will delete a segment if all docs are deleted from it; this means that we lose the deletes when deleting all docs
-                assertThat(docStats.getDeleted(), equalTo(numDocsToDelete == numDocs ? 0 : numDocsToDelete));
             }
 
             // merge them away