Don't remove OnAlarmListener mappings in the client

Removing the mapping is prone to races in keeping the state consistent
with the server. An inconsistent state can lead to multiple alarms on
the server for the same listener.

Test: atest CtsJobSchedulerTestCases doesn't fill the alarm queue with
more than one alarm.
atest CtsAlarmManagerTestCases

Bug: 154444435
Change-Id: Iaf11d5decb17fbf2366b49d9865231bf65dbdc41