Do not export `DNS_FQDN_REQUIRED` and `DNS_BOGUS_PRIV` unconditionally (#4354)

* Do not export unconditionally

Signed-off-by: Christian König <ckoenig@posteo.de>

* Check if variable is unset instead of grep for it

Signed-off-by: Christian König <ckoenig@posteo.de>

* Use bash's buld in word syntax

Signed-off-by: Christian König <ckoenig@posteo.de>

* Move export back to their brothers

Signed-off-by: Christian König <ckoenig@posteo.de>

automated install/basic-install.sh

@@ -1715,7 +1715,7 @@ finalExports() {
     # If the setup variable file exists,
     if [[ -e "${setupVars}" ]]; then
         # update the variables in the file
-        sed -i.update.bak '/PIHOLE_INTERFACE/d;/IPV4_ADDRESS/d;/IPV6_ADDRESS/d;/PIHOLE_DNS_1\b/d;/PIHOLE_DNS_2\b/d;/QUERY_LOGGING/d;/INSTALL_WEB_SERVER/d;/INSTALL_WEB_INTERFACE/d;/LIGHTTPD_ENABLED/d;/CACHE_SIZE/d;' "${setupVars}"
+        sed -i.update.bak '/PIHOLE_INTERFACE/d;/IPV4_ADDRESS/d;/IPV6_ADDRESS/d;/PIHOLE_DNS_1\b/d;/PIHOLE_DNS_2\b/d;/QUERY_LOGGING/d;/INSTALL_WEB_SERVER/d;/INSTALL_WEB_INTERFACE/d;/LIGHTTPD_ENABLED/d;/CACHE_SIZE/d;/DNS_FQDN_REQUIRED/d;/DNS_BOGUS_PRIV/d;' "${setupVars}"
     fi
     # echo the information to the user
     {
@@ -1729,8 +1729,8 @@ finalExports() {
     echo "INSTALL_WEB_INTERFACE=${INSTALL_WEB_INTERFACE}"
     echo "LIGHTTPD_ENABLED=${LIGHTTPD_ENABLED}"
     echo "CACHE_SIZE=${CACHE_SIZE}"
-    echo "DNS_FQDN_REQUIRED=true"
-    echo "DNS_BOGUS_PRIV=true"
+    echo "DNS_FQDN_REQUIRED=${DNS_FQDN_REQUIRED:-true}"
+    echo "DNS_BOGUS_PRIV=${DNS_BOGUS_PRIV:-true}"
     }>> "${setupVars}"
     chmod 644 "${setupVars}"