When files from a deleted technique are still on fs, creation of technique with same name is impossible
If a technique deletion went wrong and some of its files are still present in the file system, then a technique with the same name (derived id actually) can't be created.
This is extremely disturbing because the user doesn't have any lever about what to do to correct the problem, or what the pb is actually: from his PoV, everything is fine:
This is related to #21119
The expected behavior would be that Rudder automatically check if the technique really exists for real, and if not (ie if we are observing remaining of an old technique badly deleted), rudder should clean things up and save the new technique.
A minima, Rudder should tell the user how he could achieve his action.