Export `Replay` shim in CDN bundle to avoid breaking in loader

[mydea]

When using the new loader setup, users can toggle replay on and off.
When users ship code with replay, and later toggle replay off in the loader config, we want to avoid breaking their app.

To "fix" this, we should export a shim of the integration in the CDN bundles with replay disabled. Since we only provide a very slim API, this should be possible with very little overhead.

[AbhiPrasad]

We need to do the same with BrowserTracing too probably.