Refine the restoreCallingIdentity and clearCallingIdentity usage

1. Use final for Binder.clearCallingIdentity() to protect not being overwritten.
2. Protect it in the finally block of the try statement to avoid missing restore the CallingIdentity as exception.
3. restoreCallingIdentity back after clearCallingIdantity.

Bug: 189819183
Test: Manual

Change-Id: I9be6158eda2f93dc800799ba5ffef10f98b8941f