Fix ActionConfigStatsTests.testEqualsAndHashcode (elastic#74849)

This change fixes failing ActionConfigStatsTests.testEqualsAndHashcode by making sure we use different shrink number of shards after mutation.

Closes elastic#74817

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/ActionConfigStatsTests.java

@@ -96,7 +96,7 @@ protected ActionConfigStats mutateInstance(ActionConfigStats instance) throws IO
                 builder.setShrinkMaxPrimaryShardSize(randomPrimaryByteSize);
                 break;
             case 8:
-                builder.setShrinkNumberOfShards(randomIntBetween(0, 50));
+                builder.setShrinkNumberOfShards(randomValueOtherThan(instance.getShrinkNumberOfShards(), () -> randomIntBetween(0, 50)));
                 break;
             default:
                 throw new IllegalStateException("Illegal randomization branch");