[context] Rendering a manually created context provider element in a consumer that is a light DOM child of a provider causes an infinite loop

Nobody has claimed this yet.

### Which package(s) are affected?

Context (@lit/context)

### Description

Given a tree like the following:
```html

#shadow-root
|

#shadow-root
|
|
|

```
Consumer gets stuck in an infinite loop rerendering itself.

From my basic investigation, it appears to be caused by the `context-provider` event, but beyond that I don't know what causes it

### Reproduction

https://lit.dev/playground/#sample=examples%2Fhello-world&gist=14a287d908738aa5664a99a88c3dd561

### Workaround

Stopping propagation of the `context-provider` event via either `stopPropagation` or `stopImmediatePropagation` on the consumer element causes the issue to disappear

### Is this a regression?

No or unsure. This never worked, or I haven't tried before.

### Affected versions

lit@3.3.1, @lit/context@1.1.6

### Browser/OS/Node environment

Browser: Librewolf 144.0-1
OS: Linux

Start with the linked Lit Playground reproduction and the @lit/context package at the reported lit@3.3.1 and @lit/context@1.1.6 versions. Trace dispatch and handling of the context-provider event when a manually created provider is rendered by a light-DOM consumer, then verify that the consumer no longer rerenders indefinitely without requiring event propagation to be stopped.

Written by the indexing model from the issue text.