TriggerJobOpts: Clean up transient ByteStream configuration

Changes:

• Split the one big function in TriggerTransBSConfig.py into individual functions per system.
• Still provide a combined function merging all systems in case it's needed.
• Include only the Calo transient BS configuration and drop all the others in the standard Trigger top-level job options. AFAIK Calo is the only client of this, so running all the other conversions is just a waste of resources.

Validation:
✅ Checked that HLT Calo actually relies on this - removing transient BS cuts all calo-based chain counts even though no errors are printed and the job runs through just fine.
✅ Compared RDOtoRDOTrigger config, logs and output RDO_TRIG before and after the changes in this MR - no unexpected differences, RDO_TRIG comes out identical.

FYI @wiedenma, @damazio, @jmasik, @tbold