ProofAggregationCoordinatorService: Add poller for proof response

[gauravahuja]

Part 2 of #2241
This PR implements issue(s) #2241

Checklist

• I wrote new tests for my new core changes.
• I have successfully ran tests, style checker and build against my new changes locally.
• If this change is deployed to any environment (including Devnet), E2E test coverage exists or is included in this
  PR.
• I have informed the team of any breaking changes if there are any.

---

Note

Medium Risk
Changes the aggregation proof flow from synchronous proof retrieval to an asynchronous request+polling model, which can affect aggregation finalization timing and error/retry behavior. New background polling introduces potential ordering/backlog issues if not carefully monitored.

Overview
Decouples aggregation proof generation into two steps: ProofAggregationCoordinatorService now submits a proof request via createProofRequest (getting an AggregationProofIndex) and defers completion until a new AggregationProofPoller retrieves the proof via findProofResponse and then calls aggregationProofHandler.

Wires the poller into the service lifecycle (start/stop), removes unused L2 client parameters from ProofAggregationCoordinatorService.create, and updates the coordinator test to mock the new request/index + polling behavior.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.75510% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.85%. Comparing base (02862e9) to head (cf5506d).

Files with missing lines	Patch %	Lines
.../aggregation/ProofAggregationCoordinatorService.kt	68.75%	5 Missing ⚠️
...coordination/aggregation/AggregationProofPoller.kt	96.96%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2601      +/-   ##
============================================
- Coverage     59.12%   58.85%   -0.28%     
- Complexity     1618     1624       +6     
============================================
  Files           454      457       +3     
  Lines         18471    18579     +108     
  Branches       2013     2016       +3     
============================================
+ Hits          10921    10934      +13     
- Misses         6883     6979      +96     
+ Partials        667      666       -1     

Flag	Coverage Δ		*Carryforward flag
hardhat	96.53% <ø> (ø)		Carriedforward from 02862e9
kotlin	54.69% <87.75%> (-0.28%)	⬇️

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
.../zkevm/coordinator/app/conflation/ConflationApp.kt	0.00% <ø> (ø)
...coordination/aggregation/AggregationProofPoller.kt	96.96% <96.96%> (ø)
.../aggregation/ProofAggregationCoordinatorService.kt	64.02% <68.75%> (-1.13%)	⬇️

... and 14 files with indirect coverage changes

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[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

There are 3 total unresolved issues (including 1 from previous review).

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