SUSYTools: add default names for accessors

This fix adds default names for a couple of accessors that were previously initialised with empty names and then updated later.

• satisfies the new check from !61697 (merged) swept to master in !62681 (merged)
• started showing up once CI tests started running with AnalysisBase in 23.0, as per ATLINFR-4901, for example in !62699 (merged)
• discussed in ATLSUSYBGF-663

SUSYTools would normally target master (and isn't in the package list for Athena), but since this is a required fix for the tests also ran with 23.0 I targeted 23.0 and would ask for the sweep to master.
Please let us know if the other way around would be preferred for this case.