XML: upgrade-2.10.xsl: apply on pacemaker-2.x pengine CTS test cases

Unpopulated "instance_attributes" were in fact replaced with
a superfluous newline (corollary of handling other situations in
upgrade-2.10.xsl), which was subsequently removed manually.

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).

Also, this is the first case of cts-pengine-autofix.py's application
(whitebox-ms-ordering-move.xml).