Remove explain this vulnerability section

What does this MR do and why?

This is part of the clean up efforts, GA Vulnerability Explanation Clean up (&14418). This MR removes the previous experimental version of vulnerability explanation:

1. Explain this vulnerability
2. Vulnerability duo trigger

Remove: Explain this vulnerability	Remove: Duo Text

The is replaced with the GA version, introduced in this MR: !161345 (merged)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

⚠ Required Manual Check from a member of the TI team @darbyfrey @dpisek @sming-gitlab ⚠

• Copy the checklist from this issue: FF Cleanup Manual Test Checklist (#478761 - closed)
• Paste the items as a comment in this MR
• Complete all the manual checks

Screenshots or screen recordings

There should be no changes to the UI, it should behave the same as production:

• https://gitlab.com/gitlab-org/security-products/oxeye/dogfooding/generic/oxeye-rulez/-/security/vulnerabilities/128168629
• https://gitlab.com/gitlab-org/security-products/oxeye/dogfooding/generic/oxeye-rulez/-/security/vulnerabilities/128168668

High Confidence CWE	Other SAST

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Related to #462023 (closed)