Crmc File Installation Fix, master branch (2021.11.25.)

I made way too many mistakes on this one. 😦 This is a follow-up to !48209 (merged) and !48243 (merged).

This time around I made sure that the find_file(...) commands would start from scratch. Since as it turned out, find_file respects existing settings on a non-cache variable as well. So to make sure that it would search for all input files correctly, we have to explicitly unset any pre-existing value on that variable...

Mea culpa @ewelina. ☹ These updates caused way more trouble than they were worth...