Ensure chosen phone account is used if it is valid.

When placing an outgoing call if a phone account is specified, there was
an issue where a list of all potential phone accounts would be returned
instead of just the one the user chose.  Fixed this.

Test: Added unit test, ran broken CTS test.
Bug: 69338480
Change-Id: I81dd73cb80df463217140d8a8087cf4140084b28