Revert "Highlight all supported languages with the highlight.js worker"

Purpose of revert

Revert !131993 (merged) to resolve QA failure that is blocking deployments (gitlab-org/release/tasks#7392 (closed)).

Opened #432545 (closed) to reinstate the reverted MR.

Checklist

• Create an issue to reinstate the merge request and assign it to the author of the reverted merge request - #432545 (closed)
• If the revert is to resolve a broken 'master' incident, please read through the Responsibilities of the Broken master resolution DRI.
• If the revert involves a database migration, please read through Deleting existing migrations.
• Add the appropriate labels before the MR is created. We can skip CI/CD jobs only if the labels are added before the CI/CD pipeline is created.

Milestone info

• I am reverting something in the current milestone. No changelog is needed, and I've added a ~"regression:*" label.
• I am reverting something in a different milestone. A changelog is needed, and I've removed the ~"regression:*" label.

Related issues and merge requests