feat: Remove `unnecessary_await_in_return`

[tomarra]

Description

This is follow up from #107.

There was an ask to remove the unnecessary_await_in_return lint. Upon doing research into this it seems like the Dart team has not actually deprecated that lint just yet so we're holding off until that happens to remove it.

This ticket should be in the backlog until we see that get deprecated and then pull it in to the next release.

Requirements

• [ ] The unnecessary_await_in_return lint has been deprecated by the Dart team
• [ ] The unnecessary_await_in_return lint has been removed from Very Good Analysis
• [ ] All CI/CD checks are passing.
• [ ] There is no drop in the test coverage percentage.

Additional Context

No response