chore: lil bit of golfing on the ultra honk verifier

[Copilot]

🧾 Audit Context

Minor optimizations identified during zk verifier review of already-audited ultra honk verifier code.

🛠️ Changes Made

• Removed scalar multiplication by 1 (no-op elimination)
• Consolidated LAGRANGE_FIRST (1,2) constant term accumulation by adding scalars directly
• Batched all inversions into single modexp operation
• Removed unintended barretenberg/sol/src/honk/instance/other.sol file

No functional changes. Purely optimization-focused refactoring. No circuit changes.

✅ Checklist

• Audited all methods of the relevant module/class
• Audited the interface of the module/class with other (relevant) components
• Documented existing functionality and any changes made (as per Doxygen requirements)
• Resolved and/or closed all issues/TODOs pertaining to the audited files
• Confirmed and documented any security or other issues found (if applicable)
• Verified that tests cover all critical paths (and added tests if necessary)
• Updated audit tracking for the files audited (check the start of each file you audited)

📌 Notes for Reviewers

Changes kept minimal as code already submitted for audit. See individual commits for isolated changes:

• 699c7e2: scalar mul removal
• 6f2c350: LAGRANGE_FIRST consolidation
• 05217b8, f1a5830: inversion batching

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