Validation Example Configuration tool - fails on missing parameters due to docs PR waiting on code merge

For example, https://github.com/fluent/fluent-bit-docs/pull/2672 has a new parameter failing on the validation check as it's looking at the current Fluent Bit code base and not accounting for the waiting code changes at https://github.com/fluent/fluent-bit/pull/12287.

The checker needs to use the code merge branch as the source of truth for validating doc PRs. Attached error message in a pipeline run that was affected.