[RFPM01] Merge package added/removed methods

There are two methods to handle package added/removed from
two differnt listeners. It can use one of listener to handle the
changes. Thus, keep PackageManagerInternal#PackageListObserver
but remove the listening from ConnectivityService.

Bug: 132784544
Test: atests FrameworksNetTests
Change-Id: Ib2db85e4108f9fda731bf6667d0af0610fc79fea