Add RTA/2024.05.27 stack

Full stack release (hence using RTA directory) to include flavour tagging functionality for analysts

cc @cprouve, @abertoli, @erodrigu, @rmatev

Release checklist (to be filled by the shifter)

• release build validation (to be checked with the MR author)
• RPMs deployment
• CVMFS installation
• web pages update