Fix test for code components under new editor runtime

[Janpot]

The new editor that runs side by side with the app runtime now reloads when a component is added. This is caused by vitejs/vite#12912. Before only the app runtime reloaded, but now the editor and app are one single react tree. This PR teaches the tests to anticipate this reload.

I suppose we can live with this for now, the whole editor became more responsive at the cost of a single reload whenc reating a new component. The ways to fix it are either

• fix Fails to hmr accept virtual modules vitejs/vite#12912
• change Toolpad custom components to require a barrel file that collects all of them so that Toolpad doesn't have to create a virtual module to import them. We will likely require you to do this in Next.js.

[apedroferreira]

the whole editor became more responsive at the cost of a single reload when creating a new component

Yeah seems like a good trade-off.