DO NOT MERGE Guard against SecurityException in QuickContact

* Also removed some unused methods
* Now, all calls to getCallCapablePhoneAccounts() have been wrapped
  with a try-catch block.

Bug: 31304557

Test: throw a SecurityException manually and verify QuickContact works

Change-Id: I611ef18f88a233e7665b55727d1b9ce53f4d1d7f