fix unstable tests

[mga-chka]

Description

The aim is to improve the randomly failing test described here https://github.com/ContentSquare/chproxy/issues/341

Pull request type

Please check the type of change your PR introduces:

• [x] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe):

Checklist

• [x] Linter passes correctly
• [] Add tests which fail without the change (if possible)
• [x] All tests passing
• [] Extended the README / documentation, if necessary

Does this introduce a breaking change?

• [ ] Yes
• [x] No

Further comments

[render[bot]]

Your Render PR Server URL is https://chproxy-pr-342.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-chsroc82qv23lfgfhnvg.