[docs-verifier] False positive broken link when heading contains xref

[This run](https://github.com/dotnet/docs/actions/runs/7050161518/job/19190221338?pr=38422#step:4:8) contains a false positive for the following link:

Error: In file 'docs/fundamentals/networking/telemetry/metrics.md': Invalid link: '../../../core/diagnostics/metrics-collection.md#create-a-custom-collection-tool-using-the-net--api'.

However, the link is correct and the build itself is clean.

This is the heading itself - notice that it contains an xref link.

`## Create a custom collection tool using the .NET API`