core: LSM - remove redundant code

1) Remove "is qualified for live merge" check:
   Block commit is used since 4.2, see [1], [2].
   So "getVm().getStatus().isQualifiedForLiveSnapshotMerge()"
   check is not needed anymore.
2) Remove redundant enum check:
  a) Simplifying the "isRemoveAutoGeneratedSnapshotRequired()" method:
     There is no need to test the 2nd part in the condition that looks like:
       stage == enumA && stage != enumB
  b) After the above simplification, the method can be inlined to receive
     an even more simple code.

[1] https://bugzilla.redhat.com/1246114
[2] https://bugzilla.redhat.com/1369942

Signed-off-by: Pavel Bar <pbar@redhat.com>

backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/storage/lsm/LiveMigrateDiskCommand.java

@@ -280,7 +280,7 @@ public boolean performNextOperation(int completedChildCount) {
             return true;
         }
 
-        if (isRemoveAutoGeneratedSnapshotRequired()) {
+        if (getParameters().getLiveDiskMigrateStage() == LiveDiskMigrateStage.LIVE_MIGRATE_DISK_EXEC_COMPLETED) {
             // This lock is required to prevent CreateSnapshotForVmCommand from
             // running at the same time as RemoveSnapshotCommand
             //
@@ -326,25 +326,6 @@ private void removeImage(Guid storageDomainId, Guid imageGroupId, Guid imageId,
         }
     }
 
-    private boolean isRemoveAutoGeneratedSnapshotRequired() {
-        boolean removeSnapshotRequired = getParameters().getLiveDiskMigrateStage() == LiveDiskMigrateStage.LIVE_MIGRATE_DISK_EXEC_COMPLETED &&
-                getParameters().getLiveDiskMigrateStage() != LiveDiskMigrateStage.AUTO_GENERATED_SNAPSHOT_REMOVE_END;
-        if (removeSnapshotRequired) {
-            if (!getVm().getStatus().isQualifiedForLiveSnapshotMerge()) {
-                // If the VM is not qualified for live merge, i.e. its status is not up, the auto-generated snapshot
-                // is not removed. Removing the snapshot while the VM isn't running will end up with cold merge
-                // and this is not desired here.
-                // Once cold merge enhanced to use qemu-img commit, this limit can be removed. See BZ 1246114.
-                // This behavior can be tracked by BZ 1369942.
-                log.warn("Auto-generated snapshot cannot be removed because VM isn't qualified for live merge. VM status is '{}'",
-                        getVm().getStatus());
-                removeSnapshotRequired = false;
-            }
-        }
-
-        return removeSnapshotRequired;
-    }
-
     private void removeAutogeneratedSnapshot(CommandContext commandContext, ActionType actionType, LiveMigrateDiskParameters parameters) {
         RemoveSnapshotParameters removeSnapshotParameters = new RemoveSnapshotParameters(getParameters().getAutoGeneratedSnapshotId(),
                 getVmId());