Release v22.138.2

Fixed

• A page that opens many observable queries at once now loads them side by side. The WebSocket hub used to run each subscribe to completion before reading the next message, so a slow query held up every query behind it, and a ping or unsubscribe too. Subscriptions now establish concurrently, up to 8 per connection.
• The WebSocket hub client sent every subscription twice on connect, once without a revision and again with one when the server's Connected message arrived. The server ran every query twice and the client discarded the first answers. Subscriptions now wait for Connected and are sent once. A server that never announces itself gets them after one second, without a revision, as before.