test: nginx: Speeds up regression test in nginx.

Instead of use `sleep` it nows parser the nginx logs to figure out
whenever it start or stop. Audit log timeout was reduced to 8 seconds.
test: nginx: Points the !# to envoriment.

Instead of using a hardcoded path to Perl, using what is provided by the
environment. Avoiding problems with MacOS, where two different
versions of Perl are expected. One provided by the system and other
by MacOS ports.