tests: Ensure clippy --tests runs on integration.rs

Include the file when running clippy as well as when building with
devcli_testenv set.

Fixes: #7846

Signed-off-by: Rob Bradford <rbradford@meta.com>

cloud-hypervisor/tests/integration.rs

@@ -2,7 +2,7 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 //
-#![cfg(devcli_testenv)]
+#![cfg(any(devcli_testenv, clippy))]
 #![allow(clippy::undocumented_unsafe_blocks)]
 // When enabling the `mshv` feature, we skip quite some tests and
 // hence have known dead-code. This annotation silences dead-code