[pm] stop sending broadcast from commitPackagesLocked()

Calling activity manager to send a broadcast from inside mPm.mLock can cause a deadlock.
We can postpone the broadcast till after the installation.

BUG: 210167312
Test: builds; will monitor TV CTS dashboard
Change-Id: Ia42d1db24d4f0f98b1fc6523a5a3a859bf7fdff5