PartPropSvc Auxiliary Installation, atlas/v35r0 branch (2020.11.20.)

Re-enabled the installation of the PartPropSvc auxiliary files.

This turned out to be necessary for athena!38429 (merged).

Pinging @leggett and @fwinkl. This should be merged in, and the v35r0.001 tag should be created, as quickly as possible...