Use the same list of bridges for desktop and android

We currently have two lists of default bridges, for desktop and android builds:

• tor-browser-build.git/projects/tor-browser/Bundle-Data/PTConfigs/bridge_prefs.js for desktop builds
• tor-android-service.git/service/src/main/assets/common/bridges.txt for android

With #40436 (closed) we are going to use an intermediate file format to store default bridges, which will not require parsing javascript to use. I think we can also use the same files to get the list of bridges in android builds.

/cc @aguestuser @richard