Remove remnants of pex_policy, which was long ago shifted to used pex_config.

The main things being gotten rid of are:

Commands:

killcondor.py - used the old style pex_policy job description to identify and kill jobs.
writeNodeList.py - this was required in an early version of ctrl_orca to enumerate the nodes used (in pbs jobs, I believe).
ProvenanceRecorder.py - This was used to make database records for policy files used in a run. This was in addition to the provenance information that used to be recorded via the provenance package, which is also obsolete, since it also used pex_policy. I don't think a replacement was ever made for that package.

lsst/ctrl/orca:

PolicyUtils.py - used to get all file names listed in a policy

The ups/ctrl_orca.table needs to have pex_policy removed as a required setup.