IMS-VT: Optimize handling of orientation requests

-Invoking setInCallAllowsOrientationChange API triggers
 multiple events which send data across binder. This
 could cause performance degradations in some cases.
-Enable/disable orientation listeners when primary call
 changes

BUG: 28766890
Change-Id: I457141ec6db7b5234be6aa537d39892e61efff6e