[tor-project] meek-azure now using the cymru backend (Tor Browser 6.5.1 and 7.0a2)

[David Fifield]

With the recent releases of Tor Browser 6.5.1 and 7.0a2, Tor Browser
users will now be using the new CDN backend and bridge when they select
meek-azure. This will be a good time to monitor bridge usage and check
if anything unexpected happens.

If all goes well, we can queue up meek-amazon for the next release.