Manual sweep of !36345: Address path resolver issue in ATLASSIM-4674 and store ParamFile in HITS file metadata

Path resolver issues an error if the absolute path to a file is specified. Tweaked the preExec in test_MC16_G4FastCalo_ttbar.sh to allow the relative path to be used. This should fix ATLASIM-4674.

This merge request also adds the relative path to the FCS V2 param file to the HITS file metadata to make book-keeping easier.