Small xrdcp-related fix to !260 (periodic BW tests)

After !260 (merged) was merged, I can see (from the handler log) that the un-formatted html page is uploaded to the UpgradeRateTest area, and I'd written the code such that a formatted copy should overwrite it, but didn't take into account that xrdcp wouldn't let us overwrite. This 1-liner just makes sure the un-formatted copy is therefore not uploaded, so we don't have to overwrite it.