Improve deleting accounts from the account resolvers

[ripienaar]

Proposed change

We need to evaluate if current features around deleting accounts are sufficient.

• Are all assets correctly cleaned up during delete?
• Does nsc and nats auth have safe ways to delete accounts that properly cleans up the server?
• Is there sufficient logging and auditing events for deletes?
• We should also consider audit events and log evens for account pushes

@aricart has thoughts.

Use case

Create mature tooling for removing accounts

Contribution

No response

[aricart]

The PR for #6427 is hanging out there (right now it works with a full resolver, at least on the disk pruning when NOT using leafnodes).

As for the deletion.

• Need to verify what happens to users when the account is deleted (expecting disconnect, but not verified it)
• The server typically keeps accounts in memory, need to verify if the account gets released

The typical process for removing an account is usually to set connections to zero, update, hoping that a delete simply kills clients, because then it removes the need to update the account.

[derekcollison]

Should we look to pull in #6427?

[aricart]

Server will panic if they do a resolver that deletes, with leafnodes or other things that get messages enriched by additional data.

[aricart]

Not to be pendantic, but also part of the account removal should be the cleanup of JS assets.