Populate module_setup from the setup module rather than special code elsewhere

This small change allows for individual setup actions to populate the SETUP_CACHE and not cause a subsequent facts-gathering when not needed. This follows the standard of other facts modules as laid out in #1206 and implemented in fedfd187749654105a22be20c27e0050bc722d0a. It allows to test of the setup module has already been run even when gather_facts was explicitely disabled.