prunes list of prod vars for snapci testing
prunes list of prod vars for snapci testing

Previous iteration blindly copied over staging vars.
As long as you skip the `validate` role, that's mostly
OK, except for the staging-only Apache rules. This commit
ensures the staging-only Apache rules are NOT copied over
to the temporary prod vars file used in testing.

mark-in/securedrop-prov-upstream,mark-in/securedrop-prov-upstream,mark-in/securedrop-prov-upstream,mark-in/securedrop-prov-upstream