[python][servicebus] Update readme.python.md to convert to singleapi package

[Copilot]

Updated the ServiceBus resource manager readme.python.md to convert from multi-api to single-api package structure using the provided template.

Changes Made

• Converted to single-api structure: Removed all multi-api configurations, version-specific tags (package-2022-10-preview, package-2021-11), and batch processing directives
• Added client title: Added title: ServiceBusManagementClient (extracted from Azure SDK Python repository __all__ variable)
• Added namespace: Added namespace: azure.mgmt.servicebus
• Updated command reference: Changed from --track2 to --python in documentation
• Preserved existing configurations: Maintained modelerfour: lenient-model-deduplication: true from original file
• Reorganized YAML structure: Split configuration into logical blocks following the template format

Template Values Used

• ServiceName: servicebus
• PackageName: servicebus
• ClientName: ServiceBusManagementClient (from Azure SDK Python repo)

The updated file now follows the standard single-api package template structure while preserving necessary existing configurations.

Fixes #35694.

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[openapi-pipeline-app]

Next Steps to Merge

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[openapi-pipeline-app]

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