RULES_E3/module_name_check: use `grep -q`

Asking grep to output stuff and the piping it to /dev/null can be done better, use "grep -q".

From man grep: -q, --quiet, --silent Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the -s or --no-messages option.

While there, remove the redirection of stderr. It should be quiet anyway, and if there really is an error, we want to see it. This removes the "bash-istic" "&> /dev/null" which is a non-portable version of >/dev/null 2>&1