The recent change to feature checkers introduced a change that regressed

some tests. There was a fix for the tests that weren't staged along with

the rest of the change, meaning that once the change went in, our tests

failed.
Since they got left out, I took the opportunity to redo the approach,

which previously was to pass a local_site= argument to the feature

checker's is_feature_enabled(). However, this change instead adds a

new flag, force_check_user_local_sites, that disables the new

test-only logic that excludes Local Site memberships from the feature

calculation. This is now passed in the necessary tests.

Unit tests pass.