Stop logging RuntimeException in IMMS#onTransact()

InputMethodManagerService has had a custom hook in its #onTransact()
to log all RuntimeException except for SecurityException, probably to
be able to catch newly introduced runtime exceptions with wtf logging.

However, we haven't actually checked the log, and having a logcat
message like

  Input Method Manager Crash

is just confusing, especially when testing such an edge case in CTS.

Let's simply drop this mechanism in favor of simplicity.

Fix: 156756151
Test: manually done as follows
 1. build aosp_bluejay-trunk_staging-userdebug and flash it
 2. adb logcat -c
 3. test CtsInputMethodTestCases:InputMethodSubtypeTest
 4. adb logcat -s InputMethodManagerService:E
   -> There is no message like "Input Method Manager Crash"
Change-Id: I773ccc7ab305a496195b78966ea97522796db8d7