Deprecate DialogInterface methods in SearchManager

android.app.SearchManager implements
DialogInterface.OnDismissListener and DialogInterface.OnCancelListener
and thus exposes the methods onCancel(DialogInterface dialog) and
onDismiss(DialogInterface dialog). This was used by the SearchManager
to register itself as a listener on the search dialog, but is no
longer used.

This was an implementation detail that leaked into the public
API. Removing them would change the API, so they are deprecated instead.

Fixes http://b/issue?id=1962203