When setting a blank password, use `webserver.api.password` instead of `webserver.api.pwhash` (fixed in https://github.com/pi-hole/FTL/pull/1702)

This prevents the password from being blanked out on the command line when it has been set by an environment variable

pihole

@@ -43,7 +43,7 @@ SetWebPassword() {
         echo ""
 
         if [ "${PASSWORD}" == "" ]; then
-            setFTLConfigValue "webserver.api.pwhash" "" >/dev/null
+            setFTLConfigValue "webserver.api.password" "" >/dev/null
             echo -e "  ${TICK} Password Removed"
             exit 0
         fi