An error during validation of inbound links breaks the `docs-build` check on the `elasticsearch/9.1` branch

While [backporting a PR](https://github.com/elastic/elasticsearch/pull/135606) on the `9.1` branch of the `elasticsearch` repo, I noticed that the `docs-build` check on the PR breaks because of a [missing anchor](https://github.com/elastic/elasticsearch/actions/runs/18092958618/job/51477622918?pr=135606#step:12:129) (unrelated to the changes in the PR).

The missing anchor was added in PR [#133831](https://github.com/elastic/elasticsearch/pull/133831/files#diff-fde0caa9a886638181b8d48bee1ad72ce491ce1c30788f50dd16f82ed5a898f4R27) on the `main` branch of the `elasticsearch` repo, but the PR wasn't backported to the `9.0` and `9.1` branches. The only link I found to the missing anchor is in the `docs-content` repo in `troubleshoot/elasticsearch/file-based-recovery.md`.

Does the build break because it tries to validate the links on the `main` branch of `docs-content` against the docs on the `elasticsearch/9.1` branch?

The backport was auto-merged regardless of the error thanks to the `auto-merge-without-approval` label added by the backport tool, and the error itself doesn't affect the docs site because we build the 9.x docs from the `elasticsearch/main` branch.

However, if we're going to have this check on the `elasticsearch/9.1` branch, should we fix the error by backporting the PR that introduced the missing anchor?

(FYI: the `docs-build` check did not run on the backport for the `9.0` branch, so there was no error there.)