Re-enable skipped portions of tests

[schmittjoseph]

As part of #2914, sections of various tests have been skipped. Each of these should be investigated, properly fixed, and re-enabled.

Tests to fix

• CollectionRulePipeline_EventCounterTriggerTest

  dotnet-monitor/src/Tests/Microsoft.Diagnostics.Monitoring.Tool.UnitTests/CollectionRulePipelineTests.cs

  Lines 103 to 105 in 8e90e48

  	[Theory(Skip = "Nondeterministic")]
  	[MemberData(nameof(GetTfmsSupportingPortListener))]
  	public Task CollectionRulePipeline_EventCounterTriggerTest(TargetFrameworkMoniker appTfm)

• MultiProcessIdentificationTest

  dotnet-monitor/src/Tests/Microsoft.Diagnostics.Monitoring.Tool.FunctionalTests/ProcessTests.cs

  Line 216 in 8e90e48

  /* TESTFIX - Race condition on process termination and user-mode app processing of it.

• CancelOperation_Supports_StoppingState Skip flaky test CancelOperation_Supports_StoppingState #3013