chore(elaborator): Remove unused imports & code

[jfecher]

Description

Problem*

Summary*

Removes the #![allow_unused] now that the elaborator is reachable in the code base. Also removes some unused import and code found by new warnings afterward.

Additional Context

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[jfecher]

(Waiting to merge this until #5082 is merged to minimize the diff size for that PR)