Backport [17.0] Fix 500 error using a instance runner registration token

What does this MR do and why?

Backport of !155082 (merged) to %17.0

Backport request: https://gitlab.com/gitlab-org/release/tasks/-/issues/11610

Merge branch 'pedropombeiro/463509/fix-500-error-when-registering-instance-runner' into 'master'

Fix 500 error when using a instance runner registration token

See merge request !155082 (merged)

Merged-by: Hordur Freyr Yngvason hfyngvason@gitlab.com Approved-by: Max Orefice morefice@gitlab.com Approved-by: Rajendra Kadam rkadam@gitlab.com Approved-by: Hordur Freyr Yngvason hfyngvason@gitlab.com Reviewed-by: Max Orefice morefice@gitlab.com Co-authored-by: Pedro Pombeiro noreply@pedro.pombei.ro

(cherry picked from commit a03219cc)

1e126a2b Fix test to reproduce real-world scenario de86a9ed Fix 500 error when using a instance runner registration token

Co-authored-by: Hordur Freyr Yngvason hfyngvason@gitlab.com

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
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• Ensure the e2e:package-and-test-ee job has either succeeded or been approved by a Software Engineer in Test.

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