Ignore the test filter for RunWindowsAzureFunctionsTests

[bouwkast]

Summary of changes

This removes the ability to change the test filter that is used when running the Azure Functions Tests and it will just fallback on the default values.

Reason for change

When someone sets the test filter for a CI build to something that requires a sample project that is not an Azure Functions sample app this stage will fail at it cannot find the sample application as only Azure Function samples are build prior to this stage.
We don't build all of the sample applications when running these as that takes significant time.
We have these in their own stage because they are a pain to build and test.

19:09:24 [ERR] Target RunWindowsAzureFunctionsTests has thrown an exception
Nuke.Common.Tooling.ProcessException: Process 'dotnet.exe' exited with code 1.
   > C:\dotnet\dotnet.exe test D:\a\_work\1\s\tracer\test\Datadog.Trace.ClrProfiler.IntegrationTests\Datadog.Trace.ClrProfiler.IntegrationTests.csproj --configuration Release --framework net7.0 --filter QuartzTests --logger trx --no-build --no-restore --results-directory D:\a\_work\1\s\artifacts\build_data\results\Datadog.Trace.ClrProfiler.IntegrationTests --settings D:\a\_work\1\s\tracer\test\test.settings /property:Platform=AnyCPU
   @ D:\a\_work\1\s
Error output:
   [xUnit.net 00:00:04.64]     Datadog.Trace.ClrProfiler.IntegrationTests.QuartzTests.SubmitsTraces(packageVersion: "") [FAIL]

Implementation details

.SetFilter just always uses the default.

Test coverage

Other details

Can likely fix this betterer some how, maybe just a new separate test filter, but I actually don't know how often we actually are filtering the Azure Functions tests.

[bouwkast]

Issue came up in #7192 when doing a comprehensive test run scoped to those tests.

https://dev.azure.com/datadoghq/dd-trace-dotnet/_build/results?buildId=188384&view=logs&j=e20f8990-7a08-508f-0f98-44b28840f02f&t=fbb31288-d900-5e20-8301-48813c5a9984