Remove redundant SmokeTests

[MichaelSimons]

With the addition of the ScenarioTests, there are now some redundant tests in the SmokeTests. An example is https://github.com/dotnet/dotnet/blob/main/test/Microsoft.DotNet.SourceBuild.SmokeTests/BasicScenarioTests.cs and https://github.com/dotnet/dotnet/blob/main/test/Microsoft.DotNet.SourceBuild.SmokeTests/WebScenarioTests.cs. Other candidates to investigate are https://github.com/dotnet/dotnet/blob/main/test/Microsoft.DotNet.SourceBuild.SmokeTests/DotNetFormatTests.cs and https://github.com/dotnet/dotnet/blob/main/test/Microsoft.DotNet.SourceBuild.SmokeTests/DotNetWatchTests.cs

[akoeplinger]

There's also some duplicated logic, e.g. https://github.com/dotnet/dotnet/blob/b730eaba60aa3a41f301a2215d3266df820420a2/test/Microsoft.DotNet.SourceBuild.Tests/TestScenario.cs#L39-L44 where I made some fixes in scenario-tests: dotnet/scenario-tests@f4af055