Avoid showing dependency group annotations on workspace members in tree (#8730)
## Summary
By default, `uv tree` shows the full workspace, not _just_ the root. If
the root depended on a workspace member as a dev dependency, then we'd
still show it as `(group: dev)` in `uv tree` even if you passed
`--no-dev`, because we weren't filtering the edges in the right place.
This is still somewhat confusing, because if `root` depends on workspace
member `child` as a dev dependency, `uv tree --no-dev` still shows both.
Closes https://github.com/astral-sh/uv/issues/8719.