Enable addtional linters (#34085)

enable mirror, usestdlibbars and perfsprint 
part of: https://github.com/go-gitea/gitea/issues/34083

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/devtest/devtest.go

@@ -179,7 +179,7 @@ func prepareMockData(ctx *context.Context) {
 
 func TmplCommon(ctx *context.Context) {
 	prepareMockData(ctx)
-	if ctx.Req.Method == "POST" {
+	if ctx.Req.Method == http.MethodPost {
 		_ = ctx.Req.ParseForm()
 		ctx.Flash.Info("form: "+ctx.Req.Method+" "+ctx.Req.RequestURI+"<br>"+
 			"Form: "+ctx.Req.Form.Encode()+"<br>"+