feat: parity-db with ahash

[Klapeyron]

Overview

Updates the workspace parity-db dependency to the Midnight fork (midnightntwrk/parity-db) instead of the crates.io crate. That fork lowers the database background flush threshold from 64 → 16 and switches hashing to ahash, with the goal of more predictable WAL flushing and better hash throughput under load.

Fork PRs:

• chore: adjusted flush threshold parity-db#1
• perf: use ahash on the global LogOverlay maps parity-db#2

Upstream PR: paritytech/parity-db#250

📌 Submission Checklist

• All commits are signed off (git commit -s) for the DCO
• Changes are backward-compatible (or flagged if breaking)
• Pull request description explains why the change is needed
• Self-reviewed the diff
• I have included a change file, or skipped for this reason:
• If the changes introduce a new feature, I have bumped the node minor version
• Update documentation (if relevant)
• Updated AGENTS.md if build commands, architecture, or workflows changed
• No new todos introduced

🧪 Testing Evidence

Please describe any additional testing aside from CI:

• Additional tests are provided (if possible)

🔱 Fork Strategy

• Node Runtime Update
• Node Client Update
• Other:
• N/A

Links

[Klapeyron]

Upstream changes paritytech/parity-db#250