[Rust][CI] Reduce size of rust build artifacts in integration test

1. Rationale

The [integration test](https://github.com/apache/arrow/pull/9884/checks?check_run_id=2263730460) has a fixed size builder docker image and has builds from several Arrow implementations.

The Rust build artifacts (compiled binaries) in the integration tests still consume ~ 1GB of space even after https://github.com/apache/arrow/pull/9879 (see apitrou's comment on https://github.com/apache/arrow/pull/9884#issuecomment-813037756).

It would be nice to reduce this even more (and speed up integration test while we are at it)