Return false instead of throwing exception

The method isCalledForCurrentedUserLocked() is used to check if
callers have privilege to perform some actions. However, calling
A11ySecurityPolict#resolveCallingUserIdEnforcingPermissionsLocked
may get SecurityException when calls from different users without
permissions directly. Checking the calling UID and user without
throwing SecurityException for active a11y service instead of the
original one.

Bug: 62958230
Test: a11y CTS & unit tests

Change-Id: I0062612bc73d507db21e151dccaf6609d9e0eaf4