Remove unnecessary calls to sign out

What does this MR do and why?

Continuing the work (epic) to improve slow tests and other inefficiencies. Throughout our codebase, we make superfluous calls to sign_out (for example, signing the user out of a test in the after block). These calls are superfluous and take unnecessary time, since each new test starts a new browser session.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.