Skip native loading with embedded EC

### Your use case

#### What would you like to do?
Since EC is now embedded the widget loading time is very predictable. It is short enough to not need a native loading indicator.
#### Why would you like to do it?
Have a less flickery call start experience
- whitescreen
- native laoding icon (for half a second)
- whitescreen
- EC "Loading..." font
- Video tile with "waiting for media" loading
#### How would you like to achieve it?
Remove the native loading indicator and only have EC loading screen to reduce the steps.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

No source files, tests, or entry points are identified in the issue. Start by locating the client code that displays the native call loading indicator and the embedded EC loading screen, then confirm which clients are in scope. Done means the native indicator no longer appears during embedded EC call startup and the existing EC loading screen remains visible.

Written by the indexing model from the issue text.