fix: removing ",gw=" from GATE variable when reading/writing from/to config. (#6177)

Previously when creating a config, GATE variable would incluse ",gw="
which was crashing the installer script when read later on.
This fix:
1. writes GATE variable to config without ",gw="
2. removes ",gw=" from GATE variable when reading existing config

Co-authored-by: teohz <git@teohz.com>

misc/build.func

@@ -249,6 +249,7 @@ write_config() {
   # This function writes the configuration to a file.
   if whiptail --backtitle "Proxmox VE Helper Scripts" --defaultno --title "Write configfile" --yesno "Do you want to write the selections to a config file?" 10 60; then
     FILEPATH="/opt/community-scripts/${NSAPP}.conf"
+    [[ "$GATE" =~ ",gw=" ]] && local GATE="${GATE##,gw=}"
     if [[ ! -f $FILEPATH ]]; then
       cat <<EOF >"$FILEPATH"
 # ${NSAPP} Configuration File