fix: Do not create immutable secrets for NovaComputeNode AMQPUsers

Set copy_on_write=False for the optional_secret_ref inside yaook/op/infra/amqp_cr.py to prevent an immutable secret from being created after the NovaComputeNode resource is recreated. Otherwise the NovaComputeNode AMPQUser will become stuck in ReconcileFailed with Resources that are immutable must have randomly generated names.

Closes #630 (closed)