refactor(rebalancer-sim): Use testcontainers for anvil setup

[nambrot-agent]

Summary

Replaced spawn-based anvil process management with testcontainers, consistent with CLI e2e tests pattern.

• No local anvil installation required (uses Docker image)
• Automatic container cleanup even on test crashes
• Retry logic for CI reliability
• Consistent with how CLI e2e tests handle anvil

Addresses PR #7903 review comment from @xeno097.

Relates to ENG-3234.

Design Decision: Single Container

The rebalancer-sim intentionally uses a single anvil container with multiple virtual domains (domain IDs 1000, 2000, 3000) rather than multiple separate containers like CLI e2e tests. This is to:

1. Keep provider/signer coordination simple - All domains share one RPC endpoint, avoiding multi-provider orchestration complexity
2. Faster test execution - No multi-container startup/coordination overhead
3. Simpler state management - Single blockchain state to reason about
4. Sufficient for rebalancer testing - Tests verify rebalancer logic, not actual cross-chain message passing

The CLI e2e tests need multiple containers because they test real cross-chain scenarios. The rebalancer simulation tests the rebalancer's decision-making against synthetic scenarios on a shared state.

Changes

• typescript/rebalancer-sim/package.json - Added testcontainers dependency
• typescript/rebalancer-sim/test/utils/anvil.ts - Rewrote to use testcontainers (177 → 85 lines)

CI Workflow Note

The CI workflow change (.github/workflows/rebalancer-sim-test.yml) to remove the Foundry setup step couldn't be pushed due to token scope limitations. The change is:

-      - name: Setup Foundry
-        uses: ./.github/actions/setup-foundry
+      # Note: Foundry/anvil not needed - tests use testcontainers (Docker image)

This can be added manually or the tests will still work (Foundry setup is just unnecessary overhead now).

Testing

All tests pass locally:

• harness-setup ✅
• inflight-guard ✅
• full-simulation (extreme-drain) ✅

[hyper-gonk]

⚙️ Node Service Docker Images Built Successfully

Service	Tag
🔑 key-funder	c1dbb6c-20260203-010957
🔍 offchain-lookup-server	c1dbb6c-20260203-010957
♻️ rebalancer	c1dbb6c-20260203-010957
🚀 ts-relayer	c1dbb6c-20260203-010957
🕵️ warp-monitor	c1dbb6c-20260203-010957

Full image paths

gcr.io/abacus-labs-dev/hyperlane-key-funder:c1dbb6c-20260203-010957
gcr.io/abacus-labs-dev/hyperlane-offchain-lookup-server:c1dbb6c-20260203-010957
gcr.io/abacus-labs-dev/hyperlane-rebalancer:c1dbb6c-20260203-010957
gcr.io/abacus-labs-dev/hyperlane-ts-relayer:c1dbb6c-20260203-010957
gcr.io/abacus-labs-dev/hyperlane-warp-monitor:c1dbb6c-20260203-010957