cypress: Fix "use UI to login" anti-pattern

Keep a single test using the UI to login and add a Cypress command to login programatically because UI login is slow, cumbersome, and unnecessary.

https://docs.cypress.io/guides/getting-started/testing-your-app.html#Logging-in

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Migrated from D3331 (view on Phabricator)

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Patch application report for D3331 (id=11792)

Rebasing onto 8e0fa87b...

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commit dc860b2a38b0b1ffd08b28e6a7250493122bd98b
Author: Antoine Lambert <antoine.lambert@inria.fr>
Date:   Mon Jun 22 13:54:22 2020 +0200

    cypress: Fix "use UI to login" anti-pattern
    
    Keep a single test using the UI to login and add a Cypress command to login
    programatically because UI login is slow, cumbersome, and unnecessary.
    
    https://docs.cypress.io/guides/getting-started/testing-your-app.html#Logging-in

See https://jenkins.softwareheritage.org/job/DWAPPS/job/tests-on-diff/210/ for more details.

Thanks! I remember looking at that page the last time I ran the cypress tests ;)

Merge request was accepted

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Thanks.

Merge request was merged

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