Backport of 'Add missing ID token claims for fork MR pipelines' to 19.2

Why a maintainer can merge this

This is a bug fix backport to a maintained version, so it needs no exception request and no release manager approval. One maintainer approval is enough.

• Patch release runbook for engineers: bug fix backports to all maintained versions (N, N-1, N-2) are self-serve
• Announcement (internal): "Backport requests won't be necessary for backporting bug fixes to the maintained versions"

What does this MR do and why?

Backport of !258245 (merged) to 19.2. See it for the full context.

Customers on GitLab Self-Managed can't bind cloud trust policies, like AWS IAM, to the project that runs a merge request pipeline when the source and target projects are different, such as from a fork. This adds the source_project_* ID token claims and allows job_project_path, job_project_id, source_project_path and source_project_id as sub claim components.

Issue: #565925 (closed)

Fixes the regression in #561735 (closed)

Differences from the default branch MR, from conflicts with text that changed on the default branch after 19.2:

• The id_token_burned_project_path job failure message stays a plain string, because 19.2 does not translate those messages. No Job| string in locale/gitlab.pot.
• The reclaimed path error messages take the default branch wording. The 19.2 text named id_token_sub_claim_components instead of the ci_id_token_sub_claim_components API parameter, and linked to an anchor that does not exist.
• Adds the ID token issuance is disabled troubleshooting section to doc/ci/secrets/id_token_authentication.md. The OidcBurnedPathError message links to it, and it maps each path component to its ID component.

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).
• The MR title is descriptive (e.g. "Backport of 'title of default branch MR'"). This is important, since the title will be copied to the patch blog post.
• Required labels have been applied to this merge request
  • severity label and bug subtype labels (if applicable)
  • If this MR fixes a bug that affects customers, the customer label has been applied.
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the E2E Omnibus GitLab EE pipeline (triggered by thee2e:test-on-omnibus-ee job) has succeeded. If it has failed (or shows warnings), investigate the failures. If you determine the failures are unrelated, you may proceed. If you need assistance investigating, request help in the #s_developer_experience Slack channel to confirm the failures are unrelated to the merge request.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).
• Once the backport has been merged, the commit changes will be automatically deployed to a release environment that can be used for manual validation. See after merging runbook for details.