SipService: fix thread/socket leak

Should call SipSessionGroup.close() instead of closeNotToReceiveCalls() to stop
the SIP stack (which will stop the MessageProcessor thread and close its socket).

Might be related to ANR's reported by:
http://b/issue?id=3021924
http://b/issue?id=3021927

Change-Id: I4ead1d81fc9abac983f5753b825d20bc1cc79866
1 file changed