Don't back-off ALREADY_IN_PROGRESS syncs

BUG: 16219182
The issue is that some adapters get into a bad state where
SyncManager assumes them complete yet they are still going. This
result in ALREADY_IN_PROGRESS coming back from the adapter, the
default retry-time for which is about 10s.
Subject ALREADY_IN_PROGRESS to exponential back-off to avoid waking
up SM every ~10 seconds

Change-Id: I6cef787366436c678bac762ec6daf6212f04badc

services/core/java/com/android/server/content/SyncManager.java

@@ -2757,9 +2757,7 @@ public class SyncManager {
                 } else {
                     Log.d(TAG, "failed sync operation " + syncOperation + ", " + syncResult);
                     // the operation failed so increase the backoff time
-                    if (!syncResult.syncAlreadyInProgress) {
-                        increaseBackoffSetting(syncOperation);
-                    }
+                    increaseBackoffSetting(syncOperation);
                     // reschedule the sync if so indicated by the syncResult
                     maybeRescheduleSync(syncResult, syncOperation);
                     historyMessage = ContentResolver.syncErrorToString(