MM-13718 Prevent files from being attached to multiple posts (#10094)

* MM-13718 Prevent files from being attached to multiple posts

* Switch back to non-batched AttachToPost

* Change status code when failing to attach a file

api4/file_test.go

@@ -951,7 +951,7 @@ func TestGetFileLink(t *testing.T) {
 	CheckBadRequestStatus(t, resp)
 
 	// Hacky way to assign file to a post (usually would be done by CreatePost call)
-	store.Must(th.App.Srv.Store.FileInfo().AttachToPost(fileId, th.BasicPost.Id))
+	store.Must(th.App.Srv.Store.FileInfo().AttachToPost(fileId, th.BasicPost.Id, th.BasicUser.Id))
 
 	th.App.UpdateConfig(func(cfg *model.Config) { cfg.FileSettings.EnablePublicLink = false })
 	_, resp = Client.GetFileLink(fileId)
@@ -1143,7 +1143,7 @@ func TestGetPublicFile(t *testing.T) {
 	}
 
 	// Hacky way to assign file to a post (usually would be done by CreatePost call)
-	store.Must(th.App.Srv.Store.FileInfo().AttachToPost(fileId, th.BasicPost.Id))
+	store.Must(th.App.Srv.Store.FileInfo().AttachToPost(fileId, th.BasicPost.Id, th.BasicUser.Id))
 
 	result := <-th.App.Srv.Store.FileInfo().Get(fileId)
 	info := result.Data.(*model.FileInfo)