pkgbase: remove logic for _profile packages

We don't produce these anymore as of r356797, remove the remnant in
generate-ucl.sh that accounted for them. This isn't strictly necessary, but
future work is needed for the various packages that can be generated on a
lib build.

Namely, we may produce -development packages for private/internal libs that
should be installed but won't have the base FreeBSD-libfoo pkg to depend on
because it's internal (e.g. liby, libpmcstat, libifconfig) but we want the
headers installed. It may be a better move to just shove these into
-runtime-development instead, but if not then we've just simplified the
cases that need to take private/internal libs into account.