Fix or remove the hyp3-docs link checker

[jtherrmann]

Jira: https://asfdaac.atlassian.net/browse/TOOL-2129

Note: The above link is accessible only to members of ASF.

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The check-links workflow always fails with:

### Errors in docs/guides/rtc_product_guide.md

* [403] [https://doi.org/10.1080/01431161.2017.1404162](https://doi.org/10.1080/01431161.2017.1404162) | Failed: Network error: Forbidden
* [403] [https://doi.org/10.1080/2150704X.2016.1225172](https://doi.org/10.1080/2150704X.2016.1225172) | Failed: Network error: Forbidden
* [403] [https://doi.org/10.1080/01431161.2016.1192304](https://doi.org/10.1080/01431161.2016.1192304) | Failed: Network error: Forbidden

We should fix it or remove the workflow, so that we don't always see a failing check on our PRs.