Omit groupdel call on uninstallation

The installers don't create a group explicitly, so either both useradd
and userdel create/remove one implicitly, or neither do.

tools/publish-release

@@ -131,6 +131,5 @@ cat >"$web_root_dir/uninstall" <<-EOF
 	fi
 	rm -rf "/opt/\$rel_name"
 	userdel "\$rel_name"
-	groupdel "\$rel_name" 2>'/dev/null' || :
 	echo "\$rel_name has been uninstalled successfully."
 EOF