Add RTA/2022.12.21.3 stack

Patch release for running HLT2 in MC productions. It includes lhcb/LHCb!4246 (merged)

This is a patch stack with respect to RTA/2022.12.1_1.yml. The version schema change is aligning us to #9

See lhcb/opg#23

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