[mono] System.Diagnostics.Tests.DiagnosticSourceTest.AllSubscriberStress test very slow on Mono

[akoeplinger]

We're seeing this outerloop test hitting the timeout in CI, while it doesn't on CoreCLR:

Console log: 'System.Diagnostics.DiagnosticSource.Tests' from job 49d2aeb0-3194-4c29-a7b7-692082a2cfcb workitem a1d6acdb-00b5-4ef7-8d59-c50ce023988c (osx.1200.amd64.open) executed on machine dci-mac-build-325.local running macOS-12.4
+ ./RunTests.sh --runtime-path /tmp/helix/working/A9B40970/p
----- start Wed Dec 21 07:32:48 PST 2022 =============== To repro directly: =====================================================
pushd .
/tmp/helix/working/A9B40970/p/dotnet exec --runtimeconfig System.Diagnostics.DiagnosticSource.Tests.runtimeconfig.json --depsfile System.Diagnostics.DiagnosticSource.Tests.deps.json xunit.console.dll System.Diagnostics.DiagnosticSource.Tests.dll -xml testResults.xml -nologo -nocolor -trait category=OuterLoop -notrait category=IgnoreForCI -notrait category=failing 
popd
===========================================================================================================
/private/tmp/helix/working/A9B40970/w/BCD309D3/e /private/tmp/helix/working/A9B40970/w/BCD309D3/e
  Discovering: System.Diagnostics.DiagnosticSource.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Diagnostics.DiagnosticSource.Tests (found 19 of 244 test cases)
  Starting:    System.Diagnostics.DiagnosticSource.Tests (parallel test collections = on, max threads = 6)
   System.Diagnostics.DiagnosticSource.Tests: [Long Running Test] 'System.Diagnostics.Tests.DiagnosticSourceTest.AllSubscriberStress', Elapsed: 00:10:43
   System.Diagnostics.DiagnosticSource.Tests: [Long Running Test] 'System.Diagnostics.Tests.DiagnosticSourceTest.AllSubscriberStress', Elapsed: 00:12:45
   System.Diagnostics.DiagnosticSource.Tests: [Long Running Test] 'System.Diagnostics.Tests.DiagnosticSourceTest.AllSubscriberStress', Elapsed: 00:14:46
   System.Diagnostics.DiagnosticSource.Tests: [Long Running Test] 'System.Diagnostics.Tests.DiagnosticSourceTest.AllSubscriberStress', Elapsed: 00:16:48
   System.Diagnostics.DiagnosticSource.Tests: [Long Running Test] 'System.Diagnostics.Tests.DiagnosticSourceTest.AllSubscriberStress', Elapsed: 00:18:49
/tmp/helix/working/A9B40970/p/scripts/209a4d6b0b364075982a04795f3a8564/execute.sh: line 4: 90698 Killed: 9               ./RunTests.sh --runtime-path "$HELIX_CORRELATION_PAYLOAD"

Filing this issue to disable the test for now.