Revert "Block new Android.mk added to all directories except the directories for partners"

This reverts commit 41f2bc07.

Reason for revert: DroidMonitor: Potential culprit for http://b/404877782 - verifying through ABTD before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.

Change-Id: I0e827f2e3656a6ddf6fb0f2654dc14fc118ca499