Link CalendarAstronomer statically in the system server

Stop-gap measure to allow TwilightService to fork
the implementation of CalendarAstronomer or use its own
implementation, and remove the @CorePlatformApi.

Bug: 139480281
Bug: 134508682
Test: m droid
Change-Id: Id75fefe4f66a386a1c072f8b2e0bdbd0f642bb4b