C#: Comment out old .NET tests.

Author: michaelnebel

csharp/ql/integration-tests/all-platforms/blazor_net_8/test.py

@@ -1,2 +1,5 @@
+import pytest
+
+@pytest.mark.skip(reason="Only use .NET 10 for running tests.")
 def test(codeql, csharp):
     codeql.database.create(source_root="BlazorTest")

csharp/ql/integration-tests/all-platforms/cshtml_standalone_net6/test.py

@@ -1,2 +1,5 @@
+import pytest
+
+@pytest.mark.skip(reason="Only use .NET 10 for running tests.")
 def test(codeql, csharp):
     codeql.database.create(build_mode="none")