Replace Hard-coded HTTP Verbs with Constants (#27219)

* Replace hard-coded HTTP verbs with constants in `net/http`

server/channels/api4/upload_local.go

@@ -3,8 +3,10 @@
 
 package api4
 
+import "net/http"
+
 func (api *API) InitUploadLocal() {
-	api.BaseRoutes.Uploads.Handle("", api.APILocal(createUpload, handlerParamFileAPI)).Methods("POST")
-	api.BaseRoutes.Upload.Handle("", api.APILocal(getUpload)).Methods("GET")
-	api.BaseRoutes.Upload.Handle("", api.APILocal(uploadData, handlerParamFileAPI)).Methods("POST")
+	api.BaseRoutes.Uploads.Handle("", api.APILocal(createUpload, handlerParamFileAPI)).Methods(http.MethodPost)
+	api.BaseRoutes.Upload.Handle("", api.APILocal(getUpload)).Methods(http.MethodGet)
+	api.BaseRoutes.Upload.Handle("", api.APILocal(uploadData, handlerParamFileAPI)).Methods(http.MethodPost)
 }