[v6r12] Removed use of shifter proxy (read-only operations)

@atsareg @phicharp IIUC these agents would keep working in case of DFC. In case the file catalog is instead the LFC we need the machines to be trusted, and the agents/optimizers should run with CSEC_MECH=ID env variable

If accepted I will update the documentation.

Not using the proxy demonstrated speedup.