REGTESTS: use lua mailer script for mailers tests

Since mailers/healthcheckmail.vtc already requires lua to emulate the
SMTP server for the test, force it to use lua mailers example script
to send email-alerts so we don't rely anymore on legacy tcpcheck
mailers implementation.

This is done by simply loading examples/mailers.lua (as a symlink) from
haproxy config file.
2 files changed