Configure built-in bridges to publish descriptors and metrics

We had a volunteer point out to us the fact that most of your built-in bridges in do not publish their descriptors, and therefore you won't be able to check the overall (and country-specific) usage metrics for these bridges, and they don't have relay search pages. We've found default bridge usage metrics very useful for us to recognize and respond to blocking events.

I don't know whether you run these bridges yourselves or have volunteers or other orgs running them for you, but the fix is simple, and does not compromise the bridges or make them more likely to be blocked. All you have to do is modify the torrc file to say:
```
PublishServerDescriptor 1
BridgeDistribution none
```
This ensures that the descriptors will be collected (and therefore, metrics), but the bridges *will not* be handed out over BridgeDB. We have our built-in bridges configured this way as well. See https://gitlab.torproject.org/tpo/core/tor/-/issues/18329 for some history on this topic.

It's up to you whether you want to make this change, but we've found it to be a reliable way to determine whether and to what extent our built-in bridges have been blocked in different countries and could prove useful for responding to blocking events.