Tweak display name search experiment queries

* Display name, phonetic name, and email queries should do
  a prefix match.
* We should always try to match phone numbers and
  also start matching right away (we were waiting until the
  query looked like a phone number and also not doing both
  email and phone queries at the same time).

Bug 26697731
Bug 27324941

Change-Id: Ifdd9a3995921ba1f562fda122cbd7d6a2f4a7737