Delete or improve "How to Simulate Authentication with a Token in a Functional Test" article

[wouterj]

I propose to delete the "How to Simulate Authentication with a Token in a Functional Test" cookbook article:

• It's an alternative of "How to Simulate HTTP Authentication in a Functional Test", but it doesn't explain when to use this or the other technique.
• At the bottom, it says "The technique described in How to Simulate HTTP Authentication in a Functional Test is cleaner and therefore the preferred way." Why should we document something that's not recommended?
• The technique doesn't look clean at all.

[javiereguiluz]

I dislike the "Auth with a token" tutorial a lot. However, in complex applications the alternative "Auth in tests" technique doesn't work. I always see the first technique implemented.

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In any case, I'd merge both articles and add a brief explanation about when to use each of them.

[javiereguiluz]

Done in #7507.

[javiereguiluz]

Closing it as fixed by #7507.