casting iterate does not produce value when subscribed before node created

[mhofman]

Describe the bug

agoric follow and the various client operations that use casting to iterate streaming values of a node hangs forever and does not produce any value if the subscription is started before the node is created

To Reproduce

Steps to reproduce the behavior:

• Create an address
• agoric follow :published.wallet.${address}
• Provision a smart wallet for the address
• Perform some wallet-action

Expected behavior

The values published to the smart wallet are iterated by agoric follow

Additional context

Discovered while adding a test for auto-publish (#8574), but it looks like a general problem that applies to casting subscribe.