No longer export CallSubjectDialog

This is most likely not used outside of the app and can be potentially
exploited

Bug: 218341397
Test: Manual
Change-Id: I8c0c2bdddb172aba5a41e3fff0413eb48a5f4455
Merged-In: I8c0c2bdddb172aba5a41e3fff0413eb48a5f4455
(cherry picked from commit eadb0b1cc94deaa238bfdf225a504119a8a24388)
1 file changed