fix(gw-listener): clarify drift counter description

Address review feedback: the old wording "peer submissions or consensus
mismatch" was ambiguous. Reword to make the two detection paths explicit.

Author: Eikix

coprocessor/fhevm-engine/gw-listener/src/metrics.rs

@@ -100,7 +100,7 @@ pub(crate) static KEY_DIGEST_MISMATCH_COUNTER: LazyLock<IntCounter> = LazyLock::
 pub(crate) static DRIFT_DETECTED_COUNTER: LazyLock<IntCounter> = LazyLock::new(|| {
     register_int_counter!(
         "coprocessor_gw_listener_drift_detected_counter",
-        "Number of detected drifts from peer submissions or consensus mismatch"
+        "Number of handles where coprocessor digests diverged (peer-to-peer or local-vs-consensus)"
     )
     .unwrap()
 });