3/n: Move internal cleanup to its own ClientMonitor subclass

InternalRemovalClient and InternalEnumerateClient are only used within
InternalCleanupClient, which keeps track of the cleanup state. This
allows us to remove a lot of unnecessary global state.

Bug: 157790417
Test: Manually cause mismatched templates by modifying FingerprintUtils.
      Mismatched Framework/HAL templates are properly cleaned up.

Change-Id: I100e579f5343114644889e3527923e56bdd1972f