Remove mCurrentUserId dependency from onFinishPackageChangesInternal()

With this CL we start applying exactly the same logic among users in

  InputMethodManagerService
      .MyPackageMonitor#onFinishPackageChangesInternal()

Previously we skipped several operations when called for background
users.

No abrupt observable behavior change is expected/intended.

Bug: 350386877
Flag: EXEMPT refactor
Test: presubmit
Change-Id: I9cedf31aedce5271694e0b429a2899cf71f77252