Skip reporting onPackageUninstalled() if it's package removal.

We need to update our knowledge of package states within
onPackageUninstalled(), however if it's a removal we'll effectively be
removing this package from our knowledge of package states, without
updating our internal bookkeeping of app IDs since it's not the
onPackageRemoved() callbcak yet.

It's tricky to do the app ID removal within onPackageUninstalled(),
because we need to trigger onAppIdRemoved() upon removal from our
bookeeping, but onPackageUninstalled() may be repeated multiple times
for each user, and onAppIdRemoved() is supposed to be triggered after
onPackageRemoved() as well.

As an alternative, we can simply skip onPackageUninstalled() if we are
going to report onPackageRemoved() right after it, because package
removal should mean removing any state that the package uninstalled
callback could have updated, and conceptually packages may be removed
directly without being marked as uninstalled first (at least in certain
cases, like automatic package removal during first boot after an OTA).

Bug: 412443420
Test: presubmit
Flag: EXEMPT bugfix
Change-Id: I1c7d61fbd4e687aee13024d67db0b76e71f6617b