SensitivePhoneNumbers: Fix number comparison

* Currently, we just compare the strings for equality,
  which results in incorrect detection of sensitive nums
  a lot of the time, because adding (or removing) the
  country code is enough to make the detection fail,
  meaning the call to that phone number is logged
* Use Android's PhoneNumberUtils comparison method to
  fix this, since it takes these factors into account

Change-Id: I26ac180f8a6552cf87a4bada1d370f0ebb884ee1