Stabilize `--output-format` in `--watch` mode (#22908)
Summary
--
This PR stabilizes the changes from #21097 and closes #19552. Note that
this has
two effects:
- the default output format in `--watch` mode becomes `full` instead of
`concise`
- the `--output-format` flag will now be respected
So the default output is now more verbose, but the old stable behavior
can be
retained by passing `--output-format=concise` (or any other supported
format)
instead.
Test Plan
--
Manual testing. I think we tried to set up automated tests in an earlier
PR but
decided they were too complex.
I really should have cropped these, but I'll just collapse them instead:
<details><summary>Screenshots</summary>
<p>
### Current output, no `--output-format`
<img width="783" height="514" alt="image"
src="https://github.com/user-attachments/assets/a758daa8-534e-4dab-9cff-858321cede61"
/>
### Current output, `--output-format=json`
The same as above, the flag has no effect
<img width="783" height="514" alt="image"
src="https://github.com/user-attachments/assets/e5b0743a-6bd5-4dec-83e0-de24e44567ca"
/>
### PR branch output, no `--output-format`
Default format is now `full` rather than `concise`
<img width="783" height="514" alt="image"
src="https://github.com/user-attachments/assets/cf51947d-52e3-4420-83e7-73530557c324"
/>
### PR branch output, `--output-format=json`
JSON output, the flag works
<img width="783" height="514" alt="image"
src="https://github.com/user-attachments/assets/e7127c5a-88ad-4b2a-80b4-193b63b631ee"
/>
</p>
</details>
