test(evm): split archived StakingRewards suite

[branarakic]

Summary

• split the 4k-line archived StakingRewards test into 11 skipped suite part files
• move the shared V8 fixture/helpers into StakingRewards.shared.ts
• keep each generated .test.ts file below 500 lines

Notes

• StakingRewards.shared.ts remains larger because it preserves the original archived fixture as shared setup; further splitting that fixture would be a separate refactor.

Verification

• compared ordered skipped test titles between the original file and split files
• ./node_modules/.bin/hardhat test --no-compile --config hardhat.node.config.ts test/archive/integration/StakingRewards.part-*.test.ts

[github-actions]

Codex review skipped: filtered diff is 8991 lines (cap: 5,000). Please consider splitting this into smaller PRs for reviewability.