Fix crash when service unbinding exception happens.

If the call screening service haven't been registered, trying to unbind
it will make the device crash. Wrap the unbinding process in a try-catch
block to avoid this crash.

Bug: 161952276
Test: atest TelecomUnitTests:CallScreeningServiceFilterTest
Change-Id: Ic4d8823efc4f91a866e6d5d72a0a94cc3438d232