Related to https://gitlab.com/mx-puppet/discord/mx-puppet-discord/-/issues/117

Looks like the bridge is too quick to start and fails to initialize
itself by connecting to Synapse. It's mostly observed after a system
reboot, because Synapse (and everything else) is slower to start.

Once mx-puppet-discord fails to initialize itself, a "No relay found"
error will be observed any time you try to relay a Matrix message to
Discord. Relaying messages in the other direction (Discord to Matrix)
also fails.

With this workaround (longer delay on mx-puppet-discord startup), I
observe mx-puppet-discord working well, even after a full reboot.
Of course, a proper fix is preferable, instead of delaying by a magic
number of seconds.