Trigger policy tests on Rust files changes (#12881)

The filter for the changed-files job in the integration.yml workflow
wasn't taking into account Rust files. So changes that touched only the
policy controller weren't triggering the policy controller integration
tests, as seen in #12847

.github/workflows/integration.yml

@@ -36,6 +36,7 @@ jobs:
             .proxy-version
             go.sum
             **/*.go
+            **/*.rs
             **/Dockerfile*
             charts/**
             justfile