Wait until dialing finished before placing call

See bug for details, but currently there's a race condition in
testConnectionServiceFocusGainedWithSameConnectionService. It places two
calls, blocking until they're added and then verifying state after each
one. This works fine on phones, but fails on watches. The reason being:
the first call is still in STATE_DIALING when we try to create the
second call and CallsManager fails to create a new call when one is
currently dialing. Phones are fast enough that the first call is past
dialing, but watches are slow enough that they're always in
STATE_DIALING when we try to place the second call.

This waits until the first call is active before placing another.

Test: Ran re-ran test on swordfish, marlin, taimen
Bug: 111765062
Change-Id: I41228529fece54138920af39f0fac0d203596051