Fallback to legacy pre/postIncludes in RDOtoRDOTrigger. This will allow running in hybrid CA jobs where only trigger uses legacy config.
RDOtoRDOTrigger
Tested using https://atlas-ami.cern.ch/?subapp=tagsShow&userdata=r14179
/cc @nstyles @jcatmore @tamartin @sshaw @rbielski @fwinkl