test: fix coverage include config

[damyanpetev]

In #241 Claude did an oopsie at the end and instead of excluding the TestBed from results it messed up the include pattern and ended up covering 3rd party used packages as well 🤭

This is actually following https://learn.microsoft.com/en-us/visualstudio/test/customizing-code-coverage-analysis?view=visualstudio#include-or-exclude-assemblies-and-members instead.

Type of Change (check all that apply):

• Bug fix
• New functionality
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes)
• Documentation
• Demos
• CI/CD
• Tests
• Changelog

Component(s) / Area(s) Affected:

How Has This Been Tested?

• Unit tests
• Manual testing
• Automated e2e tests

Test Configuration:

• .NET version:
• Hosting model:
• Browser(s):
• OS:

Screenshots / Recordings

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code
• This PR includes API docs for newly added methods/properties
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes behavioral changes and the feature specification has been updated with them
• Accessibility (ARIA, keyboard navigation, focus management) has been verified

Closes #