[Sb refactor] Add Utils.isInService to mobile pipeline

This CL just adds the backend to track the Utils.isInService bit that
the old pipeline was also tracking. It is tracked in exactly the same
way as before, but with a TODO to clarify our usage in the future.

Test: MobileConnectionRepositoryTest
Bug: 238425913
Bug: 263167683
Change-Id: I9541a9148d8cb44a5e9ebeee1c824c2402f63b5a