[chore] Use linkspector to check links

[puckpuck]

Changes

Uses Linkspector instead of markdownlinkcheck to check for links. We have been having problems with flaky link checks. Linkspector should help with fewer false positives.

Merge Requirements

For new features contributions, please make sure you have completed the following
essential items:

• CHANGELOG.md updated to document new feature additions
• Appropriate documentation updates in the docs
• Appropriate Helm chart updates in the helm-charts

Maintainers will not merge until the above have been completed. If you're unsure
which docs need to be changed ping the
@open-telemetry/demo-approvers.