Revise the IllegalArgumentException check

Combining the two IllegalArgumentException check in getSigningKeySet
to mitigate the potential information leakage.

Bug: 189857801
Test: atest PackageManagerTests
Test: manually using the PoC in the buganizer to ensure the symptom
      no longer exists.
Change-Id: Ieaedb7305300a96a83f99895435c9577351831b9
1 file changed