Frozen pages shouldn't attempt to open Websocket connections to an lively.next server

**Describe the Feature**
We won't always be deploying frozen Lively pages from a Lively server -- Lively is a development, not deployment, environment (or at least it isn't the only one). Currently, I'm serving the Galyleo Dashboard pages from GCS and from a Flask server, and neither support the L2L websocket communication. So when I'm trying to debug a deployment issue (e.g., a CORS issue today) my browser console is filled with I-can't-connect websocket messages -- which hide the error I'm trying to fix.

**Graphics**
If applicable, provide screenshots/videos of similar ideas in other software.

**Implementation Details**
What I can do (haven't yet) is go into the frozen code and comment out the offending lines of JavaScript. A royal pain, but I can get it done. Frankly, it seems to me that at a minimum this should just be a flag to the freeezer.

Start by tracing the freezer and the generated JavaScript that opens L2L WebSocket connections in frozen pages. Determine how a freezer flag can suppress those connections for deployments served from GCS or Flask, then verify that frozen output no longer emits connection errors while normal Lively-server behavior remains unchanged.

Written by the indexing model from the issue text.