TrigValSteering: Find reference for ChainCompStep from cvmfs/eos by default
Make ChainCompStep
inherit from RefComparisonStep
and use the latter's configure
function to find the reference on eos or cvmfs.
Make the "rerunL1Only" tests use the default file name for chainDump output which is chainComp input. The files are already placed in eos as new references and will be automatically synchronised to cvmfs tomorrow.
To keep the special functionality of reference installed in release, which is used by a few tests (mostly for CI), add a property reference_from_release
which (if True) skips the cvmfs/eos lookup.
Fixes ATR-22833