Update the GroupApiTests to use WireMock.Net in a easier way + small layout refactoring/reformat document

[StefH]

Summary

• Update the GroupApiTests to use WireMock.Net in a simpler / shorter way
• Small layout refactoring (removed some emptylines)
• Visual Studio : reformat document

Fixes # N/A

Type of PR

• [ ] Bug Fix (non-breaking fixes to existing functionality)
• [ ] New Feature (non-breaking changes that add new functionality)
• [ ] Documentation update
• [x] Test Updates
• [ ] Other (Please describe the type)

Test Information

• [ ] My PR required test updates

.NET Version: Os Version: N/A

Signoff

• [ ] I have submitted a CLA for this PR
• [x] Each commit message explains what the commit does
• [ ] I have updated documentation to explain what my PR does
• [ ] My code is covered by tests if required
• [x] I checked StyleCop warnings on my code

[laura-rodriguez]

Hi @StefH,

Thank you so much for your contribution ⭐! I see you're a contributor to WireMock, so it's fantastic to have your feedback on usage. I'll take a look at your suggestions and proceed accordingly.

[StefH]

You're welcome.

(btw I'm the author from WireMock.Net so if you have any more questions, just add a question in the project)

[laura-rodriguez]

superseded by #640