Add RTA/2023.08.24 stack

Stack to be used for 2022 HLT2 reprocessing and 2023 HLT2. The most important MRs are flagged with the RTA/2023.08.24 milestone.

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