Check allocation rules are cleared after ILM Shrink (#41170)

Adds some checks to make sure that the allocation rules that ILM adds
before a shrink are cleared after the shrink is complete

Author: gwbrown

x-pack/plugin/ilm/qa/multi-node/src/test/java/org/elasticsearch/xpack/indexlifecycle/TimeSeriesLifecycleActionsIT.java

@@ -59,6 +59,7 @@
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.nullValue;
 
 public class TimeSeriesLifecycleActionsIT extends ESRestTestCase {
     private String index;
@@ -218,6 +219,7 @@ public void testRetryFailedShrinkAction() throws Exception {
             assertThat(getStepKeyForIndex(shrunkenIndex), equalTo(TerminalPolicyStep.KEY));
             assertThat(settings.get(IndexMetaData.SETTING_NUMBER_OF_SHARDS), equalTo(String.valueOf(expectedFinalShards)));
             assertThat(settings.get(IndexMetaData.INDEX_BLOCKS_WRITE_SETTING.getKey()), equalTo("true"));
+            assertThat(settings.get(IndexMetaData.INDEX_ROUTING_REQUIRE_GROUP_SETTING.getKey() + "_id"), nullValue());
         });
         expectThrows(ResponseException.class, this::indexDocument);
     }
@@ -461,6 +463,7 @@ public void testShrinkAction() throws Exception {
             assertThat(getStepKeyForIndex(shrunkenIndex), equalTo(TerminalPolicyStep.KEY));
             assertThat(settings.get(IndexMetaData.SETTING_NUMBER_OF_SHARDS), equalTo(String.valueOf(expectedFinalShards)));
             assertThat(settings.get(IndexMetaData.INDEX_BLOCKS_WRITE_SETTING.getKey()), equalTo("true"));
+            assertThat(settings.get(IndexMetaData.INDEX_ROUTING_REQUIRE_GROUP_SETTING.getKey() + "_id"), nullValue());
         });
         expectThrows(ResponseException.class, this::indexDocument);
     }
@@ -480,6 +483,7 @@ public void testShrinkSameShards() throws Exception {
             assertThat(getStepKeyForIndex(index), equalTo(TerminalPolicyStep.KEY));
             assertThat(settings.get(IndexMetaData.SETTING_NUMBER_OF_SHARDS), equalTo(String.valueOf(numberOfShards)));
             assertNull(settings.get(IndexMetaData.INDEX_BLOCKS_WRITE_SETTING.getKey()));
+            assertThat(settings.get(IndexMetaData.INDEX_ROUTING_REQUIRE_GROUP_SETTING.getKey() + "_id"), nullValue());
         });
     }
 
@@ -523,6 +527,7 @@ public void testShrinkDuringSnapshot() throws Exception {
             assertThat(getStepKeyForIndex(shrunkenIndex), equalTo(TerminalPolicyStep.KEY));
             assertThat(settings.get(IndexMetaData.SETTING_NUMBER_OF_SHARDS), equalTo(String.valueOf(1)));
             assertThat(settings.get(IndexMetaData.INDEX_BLOCKS_WRITE_SETTING.getKey()), equalTo("true"));
+            assertThat(settings.get(IndexMetaData.INDEX_ROUTING_REQUIRE_GROUP_SETTING.getKey() + "_id"), nullValue());
         }, 2, TimeUnit.MINUTES);
         expectThrows(ResponseException.class, this::indexDocument);
         // assert that snapshot succeeded