Relay announces own IRC join

[half-duplex]

Summary

TeleIRC announces its own IRC join in Telegram.

Standard debugging steps

How to reproduce?

1. Configure TeleIRC with SHOW_JOIN_MESSAGE=true
2. Start the relay
3. Observe that in Telegram the bot has said "* botname joins"

Expected behavior

The relay knows its own IRC nick and does not relay its own join message, since this isn't useful to people on Telegram (or this purpose would probably be better served by a /status command)

[justwheel]

I'm triaging this as an improvement instead of a bug because I think this is actually working as intended. But I get how it can be annoying and doesn't provide much value to people in the Telegram chat, so I think it is worthwhile to keep this open on the backlog.

[half-duplex]

After some network issues, here's one place it's potentially useful, announcing the end of outages:

IRC, [22 May 2022 15:32:49]
Lost connection to '#boston2600' on 'cornelius.scuttled.net'

IRC, [22 May 2022 15:40:26]
* r joins

I'm not sure what the best path would be. Maybe make both self-join and connection lost messages configurable? Replace self-joins with "Connected to x"? (Should there be a shutdown message?)

[justwheel]

Better verbosity, especially for IRC connectivity, would help. I think replacing self-joins with a "Connected to irc.example.com` is more useful.