Remove the deprecated SipDelegate methods pertaining to Dialogs

Remove deprecated APIs pertaining to closeDialog now that all
dependencies on this method have been removed.

Bug: 187747944
Test: atest CtsTelephonyTestCases
Merged-In: I2675d3bd15199c75d70560b7ba529f267ac08970
Change-Id: I2675d3bd15199c75d70560b7ba529f267ac08970