Fix IndexShardTests#testFlushTimeExcludingWaiting (#108109)

It may take less than a millisecond to acquire/release a lock with no contention,
and flush stats have only millisecond resolution, so we can't guarantee that flush
time excluding waiting is actually less than flushTime after rounding.

So, we have to relax the assertion and make it `lessThanOrEqualTo` instead of
`lessThan`

Fixes #107462

Author: arteam

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

@@ -196,7 +196,6 @@
 import static org.hamcrest.Matchers.in;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.lessThan;
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 import static org.hamcrest.Matchers.matchesRegex;
 import static org.hamcrest.Matchers.not;
@@ -4033,7 +4032,6 @@ public void testFlushOnIdle() throws Exception {
         closeShards(shard);
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/107462")
     public void testFlushTimeExcludingWaiting() throws Exception {
         IndexShard shard = newStartedShard();
         for (int i = 0; i < randomIntBetween(4, 10); i++) {
@@ -4059,9 +4057,9 @@ public void testFlushTimeExcludingWaiting() throws Exception {
                 greaterThan(0L)
             );
             assertThat(
-                "Flush time excluding waiting should less than flush time with waiting",
+                "Flush time excluding waiting should be less or equal than the flush time with waiting",
                 flushStats.getTotalTimeExcludingWaitingOnLockMillis(),
-                lessThan(flushStats.getTotalTime().millis())
+                lessThanOrEqualTo(flushStats.getTotalTime().millis())
             );
         } finally {
             closeShards(shard);