fix(functional-test): Cached signin test failing on redirect

[vpomerleau]

Because

• Sign in cached, sign in once, use a different account test was failing on the sign out step due to redirect to cached signin

This pull request

• Update the sign out function to check for redirect away from settings but allow for different destinations (email first or sign in, for example)
• Remove the refresh in the test (not needed) and replace with URL check

Issue that this pull request solves

Closes: #FXA-10064

Checklist

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• [x] My commit is GPG signed.
• [ ] If applicable, I have modified or added tests which pass locally.
• [ ] I have added necessary documentation (if appropriate).
• [ ] I have verified that my changes render correctly in RTL (if appropriate).

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