This prevents NMSTest failure due to too many TelephonyService
listeners. (Because NMS never shuts down in normal use, it doesn't
unregister its listeners.)
Bug: 152241061
Test: atest NotificationManagerServiceTest RoleObserverTest BuzzBeepBlinkTest
Change-Id: Ia5988a194aff2e5a83cf15fcd422c063a3ca14f1
Merged-In: Ia5988a194aff2e5a83cf15fcd422c063a3ca14f1
(cherry picked from commit 0580d19946)