Migrate kubernetes/runtest to pytest fixtures.

[Irakus]

📝 Description

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✨ Type of Change

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• 🐞 Bug fix – Non-breaking change which fixes an issue
• 🚀 New feature – Non-breaking change which adds functionality
• 🔨 Refactor – Non-breaking change which refactors the code base
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• 📚 Documentation update
• 🔒 Security update
• 🧪 Tests
• 🚂 CI

🧪 Testing Scenarios

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• ✅ Tested manually
• 🤖 Ran automated end-to-end tests

✅ Checklist

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• 🔍 PR title is clear and descriptive
• 📝 For internal contributors: If applicable, include the JIRA ticket number (e.g., ITEP-123456) in the PR title. Do not include full URLs
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• 📄 I have made corresponding changes to the documentation
• ✅ I have added tests that prove my fix is effective or my feature works