XML: upgrade-2.10.xsl: apply on non-1.x/2.x pengine CTS test cases

First, arrange regression.sh to rerun the conversion also with
"pacemaker-3.x" pengine test sources[*], which is important for further
refinements as upgrade-2.10.xsl gets gradually extended (to be
eventually modified for future pacemaker-4.0 migration).

• Note that since we are, in parallel, refining the 3.0 validation schema while the CTS pengine tests might have come out of sync in this regard, we cannot afford the pre-validation phase here.

Then rerun, applying changes on said test sources right away, and
also observe which source XMLs were skipped for not matching expected
"validate-with" values. From these, pick the ones eligible to have
this reset to "pacemaker-3.0" and rerun. Then, only these remain:

• clone-colocate-instance-2.xml + clone-order-instance.xml
  • requires pacemaker-next (out of scope here for now)

• order-wrong-kind.xml
  • intentionally invalid (validate-with="none")

Also, pcmk_arg_map instance attribute that has already been prohibited
in one of previous commits gets dropped (so that both the validation
passes and ./regression.sh -G cts_pengine won't trigger such change
anew), and as usual, cts-pengine-autofix.py gets rerun (merely single
hit: bundle-probe-order-2.xml).