[MSCONFIG_NEW] Exclude from the iso, for the time being

Since more than 10 years we do ship two binaries for the very same purpose in our isos: msconfig and msconfig_new.

msconfig_new was an attempt to refactor the old tool, but it got stuck rather soon and is bloating our isos since then, and consuming build-time.

My testing shows that the older version is superior in many ways compared to that refactoring attempt:
msconfig_new_is_huge.png
msconfig_new_is_more_buggy1.webm than the old one
msconfig_new_is_more_buggy2.webm than the old one
msconfig_new_is_more_buggy3.webm than the old one

Personally I think focusing on the older tool exclusively would make more sense than trying to improve that refactoring proposal.
But since one never knows what the future might bring and I did not want to step on anyones toes, I decided to just disable the build and iso-integration of the unfinished one meanwhile, instead of dumping it entirely. Although my feeling is that after 10years of waiting it's not worth waiting another 10 years with that.