tests: add CVM test for dmi_oem_strings

Add a CVM variant of the DMI OEM strings test in
integration_cvm.rs. This test creates a confidential
guest using the basic_cvm_guest! macro and invokes the
shared _test_dmi_oem_strings() wrapper to validate DMI
OEM strings behavior under CVM.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

cloud-hypervisor/tests/integration_cvm.rs

@@ -212,4 +212,10 @@ mod common_cvm {
         let guest = basic_cvm_guest!(JAMMY_IMAGE_NAME);
         _test_dmi_uuid(&guest);
     }
+
+    #[test]
+    fn test_dmi_oem_strings() {
+        let guest = basic_cvm_guest!(JAMMY_IMAGE_NAME);
+        _test_dmi_oem_strings(&guest);
+    }
 }