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

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

server/channels/api4/export_local.go

@@ -3,9 +3,11 @@
 
 package api4
 
+import "net/http"
+
 func (api *API) InitExportLocal() {
-	api.BaseRoutes.Exports.Handle("", api.APILocal(listExports)).Methods("GET")
-	api.BaseRoutes.Export.Handle("", api.APILocal(deleteExport)).Methods("DELETE")
-	api.BaseRoutes.Export.Handle("", api.APILocal(downloadExport)).Methods("GET")
-	api.BaseRoutes.Export.Handle("/presign-url", api.APILocal(generatePresignURLExport)).Methods("POST")
+	api.BaseRoutes.Exports.Handle("", api.APILocal(listExports)).Methods(http.MethodGet)
+	api.BaseRoutes.Export.Handle("", api.APILocal(deleteExport)).Methods(http.MethodDelete)
+	api.BaseRoutes.Export.Handle("", api.APILocal(downloadExport)).Methods(http.MethodGet)
+	api.BaseRoutes.Export.Handle("/presign-url", api.APILocal(generatePresignURLExport)).Methods(http.MethodPost)
 }