Follow-up from "Refactor BranchRules::BaseService to handle common pattern"

The following discussion from !145008 (merged) should be addressed:

• @ghinfey started a discussion: (+2 comments)

  We are not skipping auth here. Is this inconsistent with the update service?

We should add the ability to skip_authorization to all the ProtectedBranches services. We call these services from other services and mutations that have already authorized the action so we don't need to authorize again.