make tests put out readable StatusCodes

[romanett]

Proposed changes

Add explicit Casts to all Asserts checking for status codes, to make debugging failed tests more straightforward

simplify gds test client cert update

Related Issues

Types of changes

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] Enhancement (non-breaking change which adds functionality)
• [x] Test enhancement (non-breaking change to increase test coverage)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected, requires version increase of Nuget packages)
• [ ] Documentation Update (if none of the other choices apply)

Checklist

• [x] I have read the CONTRIBUTING doc.
• [x] I have signed the CLA.
• [x] I ran tests locally with my changes, all passed.
• [ ] I fixed all failing tests in the CI pipelines.
• [ ] I fixed all introduced issues with CodeQL and LGTM.
• [ ] I have added tests that prove my fix is effective or that my feature works and increased code coverage.
• [ ] I have added necessary documentation (if appropriate).
• [ ] Any dependent changes have been merged and published in downstream modules.

Further comments

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 54.63%. Comparing base (60689c9) to head (871d3e3).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2593 +/- ## ======================================= Coverage 54.62% 54.63% ======================================= Files 342 342 Lines 65082 65082 Branches 13350 13350 ======================================= + Hits 35553 35556 +3 + Misses 25661 25659 -2 + Partials 3868 3867 -1 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.