This reverts commit a25b11659be8887b700311180fcd3653aa9e472b.
In a discussion with Dmitry Gozman we decided to revert this and instead
proceed with the following approach:
- rename `//browser_patches/firefox` to `//browser_patches/firefox-beta`
- rename `//browser_patches/firefox-stable` folder to
`//browser_patches/firefox`
In all of the folders, we will keep the `BUILD_NUMBER` original so that
it doesn't clash on the CDN.