Follow-up from "Fix tree_restorer spec"

The following discussions from !29141 (merged) should be addressed:

• @mkaeppler started a discussion: (+10 comments)

  When we stub feature flags using the helper in spec/support/helpers/stub_feature_flags.rb, we're expecting certain arguments. If the code encounters another FF that's not stubbed, it would raise that "unexpected arguments" exception.

  To prevent that from happening, we have a default stub in https://gitlab.com/gitlab-org/gitlab/blob/bab1c8ec29e7fea30fa4f73271428b4f84cdb939/spec/spec_helper.rb#L169 that would catch this "any arguments" case. This is done before every test example in a before block.

  Now here in our RSpec::Mocks.with_temporary_scope, we don't have this fallback stub defined that's why that line was required.

  But maybe we should make it allow(Feature).to receive(:enabled?) { true } so that it is consistent with the behavior in our regular test examples scope.

• @engwan started a discussion: (+1 comment)

  @nmilojevic1 just curious why we have to stub this twice?