Profile wrapper building performance (and fix?)

[dbeltrankyl]

Hello @kinow , @VindeeR

While working on #2468, I noticed that there is this setting:

CONFIG:
 ENABLE_WRAPPER_THREADS: False

By default, it is disabled, and I think nobody has enabled it.

I was checking the associated code in JobPackageBase.submit, and I don't believe it works correctly, as it is using a different function than usual, which hasn't been updated for a while.

I think that part needs a refactor, and see if it is useful to keep, and whether it actually improves performance when building wrappers.

For normal jobs it is never updated because len(self.jobs) == 1

[kinow]

Never ever looked at that setting I think. Thanks for writing the issue for that, Dani!

[dbeltrankyl]

added a TODO for this in #2693