[Rust] [DataFusion] Simplify accumulators

[asfimport]

Replace Rc<RefCell<>> by Box<>.

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

PRs and other links:

• GitHub Pull Request #8456

_{Note: This issue was originally created as ARROW-10295. Please see the migration documentation for further details.}

[asfimport]

Andy Grove / @andygrove:
Issue resolved by pull request 8456
#8456