Run stress testing

[Aravinda-HWK]

📌 Description

This PR is to add jobs to run load testing for password-based and key-based login to an external server.

• Closes [TASK] Run the stress test with created users #222

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🔍 Changes Made

• Add a job to run load testing on an external server

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✅ Checklist (Email System)

• Core services tested (SMTP, IMAP, mail storage, end-to-end delivery)
• Security & compliance verified (auth via Thunder IDP, TLS, DKIM/SPF/DMARC, spam/virus filtering)
• Configuration & deployment checked (configs generated, Docker/Compose updated)
• Reliability confirmed (error handling, logging, monitoring)
• Documentation & usage notes updated (README, deployment, API)

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🧪 Testing Instructions

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📷 Screenshots / Logs (if applicable)

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⚠️ Notes for Reviewers

[maneeshaxyz]

LGTM.