Remove disableHLJS from FAQ

[xuhdev]

What does this PR change? What problem does it solve?

HLJS support seems having been removed from this theme already. disableHLJS doesn't do anything.

Was the change discussed in an issue or in the Discussions before?

No

PR Checklist

• [ ] This change adds/updates translations and I have used the template present here.
• [x] I have enabled maintainer edits for this PR.
• [x] I have verified that the code works as described/as intended.
• [ ] This change adds a Social Icon which has a permissive license to use it.
• [x] This change does not include any CDN resources/links.
• [x] This change does not include any unrelated scripts such as bash and python scripts.
• [ ] This change updates the overridden internal templates from HUGO's repository.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[adityatelange]

There are people using older versions of papermod, so it is been kept for now. I will make a separate section of deprecated variables to address this issue.