Add NeedPostProcess for Parser interface to improve performance of csv render (#15153)

modules/markup/markdown/markdown.go

@@ -228,6 +228,9 @@ func (Parser) Name() string {
 	return MarkupName
 }
 
+// NeedPostProcess implements markup.Parser
+func (Parser) NeedPostProcess() bool { return true }
+
 // Extensions implements markup.Parser
 func (Parser) Extensions() []string {
 	return setting.Markdown.FileExtensions