investigate decomposition of stack build into independent packages
Remove build system dependencies from tests
retire datarel, ap, and testing_endToEnd packages
I've converted the simplest case on branch tickets/DM-2636. Kian-Tat Lim probably needs to provide input on the cases where eups is being called setup packages as its not obvious [to me] what side effects are being reliable upon. lsst_distrib is the only dependent (dependee?) on this package so its priority is lower than the others.
I've partially punted and made `tests/endToEnd.py` exit cleanly if the import of eups fails.