Normalize cloud login stack URLs

[cyphercodes]

What?

Normalize k6 cloud login --stack stack inputs by removing trailing / characters before validating them with Grafana Cloud. This keeps copied stack URLs like https://my-team.grafana.net/ equivalent to https://my-team.grafana.net.

Added focused unit coverage for stack URL normalization and command coverage for login with a trailing-slash stack URL.

Why?

A trailing slash was sent to the Cloud auth API as part of X-Stack-Url, which could make an otherwise valid stack fail authentication as not found.

Checklist

• I have performed a self-review of my code.
• I have commented on my code, particularly in hard-to-understand areas.
• I have added tests for my changes.
• I have run linter and tests locally (make check) and all pass. (Ran go test ./internal/cmd/... -count=1.)

Checklist: Documentation (only for k6 maintainers and if relevant)

Not applicable; this is a CLI bug fix.

Related PR(s)/Issue(s)

Fixes #5894

[cla-assistant]

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[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
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[joanlopez]

Hi, @cyphercodes!

Thanks for the contribution. Could you please sign the CLA? Without that, we cannot move forward and get your changes merged 🙇🏻

[joanlopez]

nit; I guess here it could also make sense to throw an error, considering it invalid. In other words, perhaps we should trim only up to one slash. But I have no strong opinion, and as I cannot see any downside of this approach, lgtm!

Any thoughts? @codebien

[mstoykov]

Hi @cyphercodes without you signing the CLA we do not have any way to merge this. Which also makes reviewing it not really useful.

Sorry for the inconvience. If it isn't working for some reason you might have to retry as the cla assistant isn't very stable some days. Please do write if you are having problems so we do at least know there is a chance this will be signed.

[oleiade]

In absence of response and action from you @cyphercodes I took the liberty to create a superseeding PR, as I would really like to see this merged: #6087.

I made sure to mention you and this PR in the description and commit to give credit where it is due 🙇🏻