Revert "SYSTEM/app/Gallery2/Gallery2.apk app - update the version to target P (28...

Revert "SYSTEM/app/Gallery2/Gallery2.apk app - update the version to target P (28) or higher."

This reverts commit 7ff2227efdca7c79eafbb2713dffa2e0ac06bab4.

Reason for revert: b/122473906
  java.lang.AssertionError: Error details:
  java.lang.RuntimeException: Unable to start receiver com.android.gallery3d.app.PackagesMonitor: java.lang.IllegalStateException: Not allowed to start service Intent { act=android.intent.action.PACKAGE_CHANGED dat=package:com.android.nfc flg=0x5000010 cmp=com.android.gallery3d/.app.PackagesMonitor$AsyncService (has extras) }: app is in background uid UidRecord{bf15789 u0a43 RCVR idle change:uncached procs:1 seq(0,0,0)}
	at android.app.ActivityThread.handleReceiver(ActivityThread.java:3520)system_app_crash: Process: com.android.gallery3d

Change-Id: Ib396fb544eb85d91dbc75ef4a71c4e99d6f19998