After enabling E2EE for the first time, keep the media transform
inplace, but make it a no-op.

This simplifies the flow a little since it doesn't require a media
session restart.

Way back when, there were performance concerns when having a transform,
which is what prompted us to implement the restar mechanism, but a lot
has changed since and both audio and video frames don't need to jump
threads these days. We are still not enabling an empty transform at all
times out of precaution.

This is only permitted when testing.testMode=true in config.js

- It can throw exceptions
- It doesn't return false on things which are not Number, just on things
  that are not NaN

Fixes: https://github.com/jitsi/lib-jitsi-meet/issues/2743

When joining if there was a modification of presence just before sending the presence in the same millisecond we send later a second presence. While testing we see modifications from e2ee which cause the duplicate presence.

It doesn't get translated in the TS build, for one.

Script I used:

```python
import os

for (dirpath, dirnames, filenames) in os.walk('.'):
    if '.git' in dirpath:
        continue
    if 'node_modules' in dirpath:
        continue
    if 'dist' in dirpath:
        continue
    if 'types' in dirpath:
        continue
    for filename in filenames:
        path = os.path.join(dirpath, filename)
        if not path.endswith('.js') and not path.endswith('.ts'):
            continue
        #print(path)
        with open(path, 'r+') as f:
            #print(f)
            data = f.read()
            if '__filename' in data:
                p, ext = os.path.splitext(path)
                txt = f"'{p[2:]}'"
                print(txt)
                data = data.replace('__filename', txt)  # Assign the result back to data
                f.seek(0)
                f.write(data)
                f.truncate()
```