tests/ci: fix missing /usr/local/{sbin,bin} in freebsdci rc PATH

[guest-svmhdvn]

Summary

Currently, a lot of tests report 'skipped' due to missing binaries
in the PATH. The real issue is that /etc/rc forcibly restricts the
PATH to the base system only.

This patch re-enables a large chunk of skipped tests by adding
the missing LOCALBASE directories to the PATH so that Kyua can
discover third-party packages. It also fixes some minor rc scripting
style as per the official freebsd scripting guide[0].

[0] https://docs.freebsd.org/en/articles/rc-scripting

Signed-off-by: Siva Mahadevan <[e-mail]>
Sponsored by: The FreeBSD Foundation

[guest-svmhdvn]

I've added a stack of diffs here. Let me know if I need to add all reviewers to each review in the stack. I didn't want to spam everyone, so I've left it like this.

[bofh]

I think this one(tests/ci: fix missing /usr/local/{sbin,bin} in freebsdci rc PATH) can land without further actions/discussions. Although I will need to check others.