Draft: Cleanup MVD online unpacker (harcoded config fallback, ...)

MR should be used to bring a cleaned up version of the MVD online unpacker and its config.
Starting point based on discussions in !2097 (merged). Further work should be done by @ajit.kumar, @s.zharko, which should both have the proper access rights once I enable all developers to work in the branch (and eventually Benedikt from MVD depending on how his analysis progress)

Included for now;

• Cleanup the fallback which where added

Reason for branch in main repo and not of fork: edition rights management VS fork/project memberships

Redmine: Refs #3564 (initial issue), #3727 (up to date params for May 2025), ...