Setup automatic generation of build pod secret

[consideRatio]

When starting up binderhub-service, we typically see this. I'm not fully read up here, but I think this is to ensure communication between binderhub and the build pod it creates. If however binderhub restarts and it re-generates such secret, it may not be able to communicate with build pods or similar. I'm really not sure atm, but the idea is that if we need some secret, and that should persist between restarts, we should make the chart generate it just like z2jh does for the token shared between hub/proxy for example.

[W 240712 12:30:22 app:702] Generating random build token secret. Set BinderHub.build_token_secret to avoid this warning.

Action points

• Figure out what this secret is about, and if it makes sense to auto-generate it.
• Auto generate it like done in z2jh