Suppress MSTEST0003 for the private manual PnP helper in UnitTest

TestPnpPropertiesInLoop is a manual stress helper kept private so MSTest doesn't auto-run it (PnP enumeration is environment-dependent). The MSTest analyzer flags MSTEST0003 ('test method signature is invalid') because a [TestMethod] must be public. Keep the method private (preserving behavior - it is never auto-discovered) and the [TestMethod] for easy ad-hoc runs, wrapping it in a scoped pragma to suppress MSTEST0003 with an explanatory comment.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Sergio0694

src/Tests/UnitTest/TestComponentCSharp_Tests.cs

@@ -4409,6 +4409,10 @@ public void TestEventRemovalByEventSource()
         //    }
         //}
 
+        // 'TestPnpPropertiesInLoop' is a manual stress helper kept 'private' so MSTest doesn't auto-run it
+        // (PnP enumeration is environment-dependent). The '[TestMethod]' is retained for easy ad-hoc runs, so
+        // suppress MSTEST0003 ("test method signature is invalid") for this intentionally-private method.
+#pragma warning disable MSTEST0003
         [TestMethod]
         private async Task TestPnpPropertiesInLoop()
         {
@@ -4417,6 +4421,7 @@ private async Task TestPnpPropertiesInLoop()
                 await TestPnpPropertiesAsync();
             }
         }
+#pragma warning restore MSTEST0003
 
         private async Task TestPnpPropertiesAsync()
         {