Overhaul Spec Tests

[MatthewKennedy]

• Ensure locale is set back to :en after tests that change the locale to :fr.
• Rename log_out to log_out_via_frontend_user_menu to avoid tests on admin side using it by mistake.
• Update some old tests to modern Rspec syntax.
• Lint some files (mostly to re-run tests).

Fix Admin Sign Out spec, it was not testing the sign out from the admin side, rather it was logging in, redirecting to the frontend and logging back out again.

Now creates an admin user, logs into the admin, redirects to the admin as expected, and then logs out from the admin UI