chore: disable Firefox WebTransport interop tests (#2930)

Firefox 134.0 has broken interop as it can no longer dial go-libp2p via WebTransport.

The regression is fixed in Firefox Nightly (136.0) so disable Firefox WebTransport interop testing until that has been released and Playwright has upgraded the version it supports (likely some time in March) or until go-libp2p ships a fix that allows dialling it again.

Author: achingbrain

interop/firefox-version.json

@@ -2,10 +2,6 @@
   "id": "firefox-js-libp2p-head",
   "containerImageID": "firefox-js-libp2p-head",
   "transports": [
-    {
-      "name": "webtransport",
-      "onlyDial": true
-    },
     {
       "name": "webrtc-direct",
       "onlyDial": true