YARN-9301. Too many InvalidStateTransitionException with SLS. Contributed by Bilwa S T.

(cherry picked from commit 96bbc3bc972619bd830b2f935c06a1585a5470c6)

hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/resourcemanager/MockAMLauncher.java

@@ -29,7 +29,6 @@ import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
 import org.apache.hadoop.yarn.security.AMRMTokenIdentifier;
 import org.apache.hadoop.yarn.server.resourcemanager.RMContext;
 import org.apache.hadoop.yarn.server.resourcemanager.amlauncher.AMLauncherEvent;
-import org.apache.hadoop.yarn.server.resourcemanager.amlauncher.AMLauncherEventType;
 import org.apache.hadoop.yarn.server.resourcemanager.amlauncher.ApplicationMasterLauncher;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttempt;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptEvent;