Modify call cleanup when emergency call dialed.

Modifying the emergency dial code to drop only self-managed calls when
an emergency call is placed.  The previous code would drop anything from
a phone account other than the one being dialed.  At the point this code
ran, however, there was no phone account selected and no binding, so the
disconnect code was not working.

Realistically we only need to drop self-managed calls.

Bug: 76442553
Test: Manually reproduced issue to observe double disconnect signal.
Change-Id: Ia92dcd95cbcce27381fb22606a668ee3e8b9426b