Use release flag for prefetcher benchmark (#1547)

Harmonises the use of `--release` compile time flag across benchmarks.

Does not need a Changelog entry, as it neither changes existing
behaviour nor is customer-facing.

---

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Signed-off-by: Christian Hagemeier <[email protected]>

Author: c-hagem

benchmark/benchmarks/prefetch_benchmark.py

@@ -23,6 +23,7 @@ def run_benchmark(self) -> None:
         subprocess_args = [
             "cargo",
             "run",
+            "--release",
             "--example",
             "prefetch_benchmark",
             self.common_config['s3_bucket'],