tests/sys/audit: add missing comma delimiter between fields

This makes the kyua report --verbose output a lot easier to parse when
looking at failed tests. It also fixes the closefrom() test since I
tested my changes with this commit but forgot to push it together with
fa32350347b4e351a144b5423f0fb2ca9d67f4ca.

Fixes: fa32350347b4 ("close_range: add audit support")