[Bug]: search in progress shouldn't say "No matching results"

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

While a search (Unified search) is still in progress, it should NOT show "No matching results".
This is misleading, indicating that the search is finished and it won't help to continue waiting for results.

"Search in progress..." would be a much better label.

Steps to reproduce

1. click the "Unified search" on the upper right
2. type a string which will only be found in files, not in contacts or anywhere else (at least on my instance with many, many files it takes the longest to find a file)
3. you'll see "No matching results" for a couple of seconds until results start appearing

Expected behavior

Simple show "Search in progress...". Only switch to "No matching results" finally no results have been found and further waiting can't yield results.

Nextcloud Server version

33.0.0 beta 5

Additional info

See also:

• #41651
• #45946

Start from the Unified search interface and reproduce the reported delay using a query that returns file results slowly. Trace how the interface distinguishes an in-progress search from a completed search with no results. Done means the pending state shows “Search in progress...” and “No matching results” appears only after the search finishes empty.