DEV: Isolate multisite specs (PR #13634)

Mixing multisite and standard specs can lead to issues (e.g. when using fab!)

Disabled the (upcoming) rubocop rule for two files that have thoroughly tangled both types of specs.


Why does moving type: :multisite from a context to a parent description makes the spec forget sign_in helper?? :scream_cat:


  1) UploadsController#show_short s3 store when upload is secure and secure media enabled when running on a multisite connection redirects to the signed_url_for_path with the multisite DB name in the url
     Failure/Error: sign_in(user)

       undefined method `sign_in' for #<RSpec::ExampleGroups::UploadsController::ShowShort::S3Store::WhenUploadIsSecureAndSecureMediaEnabled::WhenRunningOnAMultisiteConnection:0x00005565f083cf38>
     # ./spec/requests/uploads_controller_multisite_spec.rb:24:in `block (6 levels) in <main>'
     # ./spec/rails_helper.rb:279:in `block (2 levels) in <top (required)>'
     # ./vendor/bundle/ruby/2.7.0/gems/webmock-3.13.0/lib/webmock/rspec.rb:37:in `block (2 levels) in <top (required)>'

“Mystery” solved 🤦 type: :multisite replaces the implicit type: :request. Solution: type: [:multisite, :request]