Resolve race conditions in concurrent indexer_metrics_collector calls

[francisdouglas-ux]

Problem & Goal

Implement memory queue locks in indexer_metrics_collector to handle concurrent event inserts without conflicts.

Context & Components

• Target Repository: escrow-backend
• Module/Component: indexer_metrics_collector (Poller performance telemetry tracker)

Implementation Details

1. Review the existing codebase inside the escrow-backend directory.
2. Locate the source files relating to indexer_metrics_collector.
3. Implement the feature logic/validation rules step-by-step.
4. Ensure code conforms to codebase patterns (lints, formats, types).

Verification & Testing Requirements

• Validation check: Assert concurrent event notifications do not duplicate entries.
• Add comprehensive test cases matching these validation requirements.
• Ensure all other existing project tests continue to compile and pass.

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Note: This issue is completely self-contained and does not block or require any other issues to be resolved.

[thelight08]

@thelight08 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Please assign me boss😭😭🤲

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[jonah-Elisha10]

@jonah-Elisha10 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

HI MAINTAINER, I CAN DO THE JOB

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[zakarimaureen1-blip]

@zakarimaureen1-blip has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Please assign this to me

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[drips-wave]

Congratulations, @jonah-Elisha10! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

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[drips-wave]

This issue has been completed by @jonah-Elisha10 as part of the Stellar Wave Program's 8th Wave 🥳

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