ci: restore preview <-> testnet relaying

[conorsch]

As the IBC implementation comes together, we'd like to have automatic relaying between preview and testnet. We used to have this, based on the go-relayer #2308, but compatibility broke and we never restored it. Today, it'd be useful to have automatic client creation between preview and testnet, for cuiloa development: testnet contains ibc client info, but preview doesn't.

For the relayer software, use hermes. Importantly, we want to use the last-known working version of our Hermes fork: https://github.com/penumbra-zone/hermes . We plan to work on upstreaming Penumbra support to Hermes, but that work isn't done yet (#3477).

Subtasks

• Create and publish container image for hermes fork, as ghcr.io/penumbra-zone/hermes - ci: add container build workflow for fork hermes#24
• Write startup scripts to handle new-channel creation for a new preview/testnet connection
• Clear out old rly build scripts (optional)
• Deploy

[conorsch]

We need to land #3477 first, then this is unblocked.

[avahowell]

#3477 is done now, we should try re-enabling relaying using penumbra-zone/hermes main once the new testnet + testnet preview is launched.

[conorsch]

This work didn't get far: I was sidetracked debugging ICT test failures, and hunting down a regression in the Hermes timeout behavior: #4310 While 4310 is higher priority, this work technically isn't blocked on 4310: we can still try to wire up the testnet/preview channels, even if they close early.