Please remove two offline bridges

Today TB failed to reach these bridges and hung bootstrapping:

11/2/18, 22:17:36.994 [WARN] Proxy Client: unable to connect to 102.253.68.166:43775 ("general SOCKS server failure") 11/2/18, 22:19:15.344 [WARN] Proxy Client: unable to connect to 24.154.179.248:44673 ("general SOCKS server failure")

After restarting TB the PT exited without visible reason in the log:

11/2/18, 23:18:31.903 [NOTICE] Opening Socks listener on 127.0.0.1:9150 
11/2/18, 23:18:32.791 [WARN] The communication stream of managed proxy './TorBrowser/Tor/PluggableTransports/obfs4proxy' is 'closed'. Most probably the managed proxy stopped running. This might be a bug of the managed proxy, a bug of Tor, or a misconfiguration. Please enable logging on your managed proxy and check the logs for errors. 
11/2/18, 23:18:33.858 [NOTICE] Bootstrapped 5%: Connecting to directory server 
11/2/18, 23:18:33.861 [WARN] We were supposed to connect to bridge '$bridge:443' using pluggable transport 'obfs4', but we can't find a pluggable transport proxy supporting 'obfs4'. This can happen if you haven't provided a ClientTransportPlugin line, or if your pluggable transport proxy stopped running. 
11/2/18, 23:18:33.861 [WARN] Problem bootstrapping. Stuck at 5%: Connecting to directory server. (Can't connect to bridge; PT_MISSING; count 1; recommendation warn; host $relay at $address:443)

Nov 02 23:19:53.000 [info] launch_managed_proxy(): Managed proxy at './TorBrowser/Tor/PluggableTransports/obfs4proxy' has spawned with PID '5276'.
Nov 02 23:19:54.000 [debug] pt_configure_remaining_proxies(): Configuring remaining managed proxies (1)!
Nov 02 23:19:54.000 [info] notify_waitpid_callback_by_pid(): Child process 5276 has exited; running callback.

Will file a separate ticket for that, because it's related to #25502 (moved).