Adjust the markdown processor to have 1 regex for all cross-project links
    
    Until now we had two regex/extensions for the cross-project links. One
    for forks one for regular project but this lead to the situation where
    if you have a pattern such as <user>/<project>#<id> the first part
    (<user>) would be linked to the fork of the project <project> of that
    user and the second part (<project>#<id>) would link to the ticket/PR
    with this id in the original project.
    That was because the regex for cross-link project was matching the
    content of the link generated by the cross-link fork.
    By moving to one regex for all, we fix this situation.