Assert translog stats busily (#45809)

If soft-deletes is enabled, we will trim translog above the local
checkpoint of the safe commit immediately. However, if the translog
durability is async, the last commit might not be the safe commit as the
local checkpoint won't advance until translog is synced. Therefore, we 
need to verify translog stats busily.

Closes #45801
Relates #45473

Author: dnhatn

server/src/test/java/org/elasticsearch/indices/state/OpenCloseIndexIT.java

@@ -352,8 +352,7 @@ public void testOpenCloseIndexWithBlocks() {
         }
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/45801")
-    public void testTranslogStats()  {
+    public void testTranslogStats() throws Exception {
         final String indexName = "test";
         createIndex(indexName, Settings.builder()
             .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, 0)
@@ -375,16 +374,20 @@ public void testTranslogStats()  {
             }
         }
 
-        IndicesStatsResponse stats = client().admin().indices().prepareStats(indexName).clear().setTranslog(true).get();
-        assertThat(stats.getIndex(indexName), notNullValue());
-        assertThat(stats.getIndex(indexName).getPrimaries().getTranslog().estimatedNumberOfOperations(), equalTo(
-            softDeletesEnabled ? uncommittedOps : nbDocs));
-        assertThat(stats.getIndex(indexName).getPrimaries().getTranslog().getUncommittedOperations(), equalTo(uncommittedOps));
+        final int uncommittedTranslogOps = uncommittedOps;
+        assertBusy(() -> {
+            IndicesStatsResponse stats = client().admin().indices().prepareStats(indexName).clear().setTranslog(true).get();
+            assertThat(stats.getIndex(indexName), notNullValue());
+            assertThat(stats.getIndex(indexName).getPrimaries().getTranslog().estimatedNumberOfOperations(), equalTo(
+                softDeletesEnabled ? uncommittedTranslogOps : nbDocs));
+            assertThat(stats.getIndex(indexName).getPrimaries().getTranslog().getUncommittedOperations(), equalTo(uncommittedTranslogOps));
+        });
 
         assertAcked(client().admin().indices().prepareClose("test"));
 
         IndicesOptions indicesOptions = IndicesOptions.STRICT_EXPAND_OPEN;
-        stats = client().admin().indices().prepareStats(indexName).setIndicesOptions(indicesOptions).clear().setTranslog(true).get();
+        IndicesStatsResponse stats = client().admin().indices().prepareStats(indexName).setIndicesOptions(indicesOptions)
+            .clear().setTranslog(true).get();
         assertThat(stats.getIndex(indexName), notNullValue());
         assertThat(stats.getIndex(indexName).getPrimaries().getTranslog().estimatedNumberOfOperations(),
             equalTo(softDeletesEnabled ? 0 : nbDocs));