Update extension after Firefox 128 ESR is no longer available

See https://searchfox.org/mozilla-central/rev/1d3c8311925d252ae79c223a53b65e667c810805/devtools/server/actors/root.js#138-146
```js
// @backward-compat { version 142 } Process Descriptor's `getWatcher()`
// supports a new 'enableWindowGlobalThreadActors' flag to enable
// the WindowGlobal's thread actors when debugging the whole browser.
// This was actually changed in 137, but we support it for VSCode until
// ESR 140 is the only ESR available.
// This should happen when Firefox 143 gets released.
// Contact Holger Benl (hbenl) to make sure the VS Code extension is
// updated.
supportsEnableWindowGlobalThreadActors: true,
```

@hbenl can you please close this issue once the extension is updated to assume that all servers `supportsEnableWindowGlobalThreadActors` by default, without checking the trait?

That should only be done once ESR128 is EOL (https://whattrainisitnow.com/release/?version=esr). Currently that's September 16 2025.