remove request duplicates

[AdoAdoAdo]

Reasoning behind the pull request

Proposed changes

Testing procedure

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?

[Copilot]

Pull request overview

This PR reduces duplicate network requests during syncing by (1) gating the sync-stuck watchdog when there is a known backlog already handled by normal sync, and (2) coalescing concurrent “equivalent proof by nonce” requests so only one in-flight network request is performed per nonce+shard key. It also adds targeted tests to validate both behaviors.

Changes:

• Gate shouldTryToRequestHeaders() for unsynchronized nodes when ProbableHighestNonce() > currentCommittedNonce() to avoid watchdog-triggered duplicate header requests.
• Add in-flight coalescing for RequestEquivalentProofByNonceForEpoch() via a per-key reservation map to suppress duplicate proof requests.
• Add tests covering watchdog gating and proof-request coalescing behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
process/sync/resyncRecovery_test.go	Adds tests for watchdog gating behavior and lookahead proof-request windowing.
process/sync/baseSync.go	Gates watchdog header requests for unsynchronized nodes when a backlog is already known.
dataRetriever/requestHandlers/requestHandler.go	Adds in-flight deduplication for equivalent-proof-by-nonce requests and refactors request flow.
dataRetriever/requestHandlers/requestHandler_test.go	Adds concurrency tests ensuring proof-by-nonce requests are coalesced and reservations are released.

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