BUG/MINOR: proxy: respect the proper format string in sig_pause/sig_listen

When factoring out the pause/resume error messages in commit 775e00158
("MAJOR: signals: use protocol_pause_all() and protocol_resume_all()")
I forgot that ha_warning() and send_log() take a format string and not
just a const string. No backport is needed, this is 2.3-dev.
1 file changed