tests/sys/netpfil: unskip tests that no longer need to be skipped
All of these are passing consistently in the latest CI environment
in 15 back-to-back test runs.
Signed-off-by: Siva Mahadevan <me@svmhdvn.name>
PR: 260458, 260459, 260460, 264805
Sponsored by: The FreeBSD Foundation
Pull Request: https://github.com/freebsd/freebsd-src/pull/1788