Disable LongProcessNamesAreSupported on OSX (#113600)

This is consistently failing on osx after updating Helix to osx13.

Author: MichalStrehovsky

src/libraries/System.Diagnostics.Process/tests/ProcessTests.cs

@@ -2267,6 +2267,7 @@ public void TestLongProcessIsWorking()
         [Fact]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/52852", TestPlatforms.MacCatalyst)]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/53095", TestPlatforms.Android)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/29383", TestPlatforms.OSX)]
         public void LongProcessNamesAreSupported()
         {
             string sleepPath;