[Rust] [DataFusion] Fix benchmarks

[asfimport]

They are only benchmarking planning, not execution.

Reporter: Jorge Leitão / @jorgecarleitao
Assignee: Jorge Leitão / @jorgecarleitao

PRs and other links:

• GitHub Pull Request #8452

_{Note: This issue was originally created as ARROW-10293. Please see the migration documentation for further details.}

[asfimport]

Andy Grove / @andygrove:
Issue resolved by pull request 8452
#8452