fix(test): Fix the `on second attempt canonical form is used` test. (#4742) r=@philbooth
fix(test): Fix the `on second attempt canonical form is used` test. (#4742) r=@philbooth

What is the problem?
The problem seems to be the denormalized email is being overwritten
in localStorage at some point during the settings page load. The
settings page performs a lot of XHR requests, any of which could
introduce sufficient latency to cause problems.

How does this fix it?
Denormalize the email on the signin page, which makes fewer requests.
Once the email is denormalized on the signin page, refresh the page.

fixes #4711
mozilla/fxa-content-server,mozilla/fxa-content-server,shane-tomlinson/fxa-content-server,mozilla/fxa-content-server,shane-tomlinson/fxa-content-server,shane-tomlinson/fxa-content-server