Add some tests for input trimming in LostController.php

[jtrees]

Summary

Provides tests for the changes made in #37495 (thanks @joshtrichards).

Note: This is my first code contribution to nextcloud. Let me know if I should be doing something differently.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[blizzz]

failing tests unrelated / temporary infra issue

[welcome]

Thanks for your first pull request and welcome to the community! Feel free to keep them coming! If you are looking for issues to tackle then have a look at this selection: https://github.com/nextcloud/server/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22