Move database settings from models to setting (#7806)

* move database settings from models to setting

* update docs

* fix checkout pr

* fix tests

* fix lint

* remove unsupported tidb options

* correct wrong variable name

* remove tidb totally

cmd/cmd.go

@@ -38,7 +38,7 @@ func initDB() error {
 
 func initDBDisableConsole(disableConsole bool) error {
 	setting.NewContext()
-	models.LoadConfigs()
+	setting.InitDBConfig()
 
 	setting.NewXORMLogService(disableConsole)
 	if err := models.SetEngine(); err != nil {