fix: Delete the pipeline along with its all versions. Fixes #11665

[milinddethe15]

fixes #11665

Description of your changes:

• Adds a cascade parameter in deletepipeline API
• Handles delete dialog based on pipeline along with its versions
• Fixes error while deleting pipeline containing versions

Follow up PR based on: #11745

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[google-oss-prow]

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[milinddethe15]

Screen.Recording.2025-06-27.at.23.24.43.mov