Env override initial setting (#6163)

* check for overridden environment variable

fixes #6161

* Environment variable overriding a setting

Fixes #6161

packages/rocketchat-lib/server/functions/settings.coffee

@@ -17,8 +17,9 @@ RocketChat.settings._sorter = {}
 RocketChat.settings.add = (_id, value, options = {}) ->
 	# console.log '[functions] RocketChat.settings.add -> '.green, 'arguments:', arguments
 
-	if not _id or not value?
-		return false
+	if not _id or
+		not value? and not process?.env?['OVERWRITE_SETTING_' + _id]?
+			return false
 
 	RocketChat.settings._sorter[options.group] ?= 0