do not assert on indexer state (#44854)

remove the unreliable check for the state change

fixes #44813

Author: Hendrik Muhs

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexing/AsyncTwoPhaseIndexerTests.java

@@ -393,7 +393,6 @@ public void testFiveRuns() throws InterruptedException {
             indexer.start();
             assertThat(indexer.getState(), equalTo(IndexerState.STARTED));
             assertTrue(indexer.maybeTriggerAsyncJob(System.currentTimeMillis()));
-            assertThat(indexer.getState(), equalTo(IndexerState.INDEXING));
             assertTrue(awaitBusy(() -> isFinished.get()));
             indexer.assertCounters();
         } finally {