SystemServer: Get rid of some unused config.* knobs.

They are untested and were committed as part of a legacy refactoring
that appears incomplete.

The Wear team have added a few new config.* flags to disable services
they don't need on watches. These should probably be unified since we
don't really need this fine level of granularity.

Test: make & flash
Bug: 64052650
Change-Id: I5c8ed3f0e78c2ed0d2e733939a82e1ab8940de22