refactored profile update tests and their poms

1st of a potential series of prs -- note, it is a known issue that `(By.CSS_SELECTOR, '.notice.success p')` doesn't consistently display when a profile's username/website are updated. I've spoken with @Osmose about this. 

I would like to collect additional metrics on the frequency of the occurrence of these failures as well as define a reliable set of manual steps to reproduce. This is imho a low risk experiment due to it only effecting `dev` and `stage` facing jobs + there is little to no new development work planned for Affiliates until at minimum next year save for major regressions in core site functionality.
store the value of profile_page.profile_username to use in the assert and the message, it reduces selenium traffic and possible flakiness