Fix: Delete State From State File (FrontendNIC)

[mugeshsp]

Reason for Change:
This PR implements a comprehensive DeleteEndpointState API in CNS (Container Network Service) to improve endpoint lifecycle management in stateless CNI scenarios. The changes include creating the Delete Endpoint State API, handler, and helper functions, along with integrating the functionality into the network manager with proper validation for FrontendNIC scenarios.

• [x ] uses conventional commit messages
• includes documentation
• adds unit tests
• relevant PR labels added

Notes:

• feat: Add conditional check for NIC type (FrontendNic) - Enhanced the deletion of state file logic to specifically target NodeNetworkInterfaceFrontendNIC types, ensuring only appropriate endpoints are cleaned up through the CNS API
• Added DeleteEndpointState method to enable HTTP DELETE requests to the CNS endpoint API
• Implemented DeleteEndpointStateHandler and DeleteEndpointStateHelper and to handle HTTP DELETE requests for endpoint cleanup
• Tested and confirmed that the deletion of endpoints takes place in the environment

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[Copilot]

Pull Request Overview

This PR implements a DeleteEndpointState API in CNS to improve endpoint lifecycle management for stateless CNI scenarios. The changes enable proper cleanup of endpoint state files through HTTP DELETE requests with validation for FrontendNIC types.

• Adds DeleteEndpointState method to CNS client for HTTP DELETE requests
• Implements DeleteEndpointStateHandler and helper functions in REST server
• Integrates endpoint deletion into network manager with FrontendNIC validation

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
network/manager.go	Adds conditional endpoint deletion logic for FrontendNIC types in stateless CNI mode
cns/restserver/ipam.go	Implements HTTP DELETE handler and helper function for endpoint state management
cns/client/client.go	Adds client method to send DELETE requests to CNS endpoint API

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[Copilot]

The request body decoding appears unnecessary for a DELETE operation. Consider removing this unused variable and the associated decode logic (lines 1349-1354) since DELETE requests typically don't require request body parsing for endpoint deletion.

Suggested change

	err = service.DeleteEndpointStateHelper(endpointID)
	// Delete the endpoint from state
	err := service.DeleteEndpointStateHelper(endpointID)

[behzad-mir]

Look good overall. Need to address the changes I mentioned.

[behzad-mir]

Please address the Lint erros in the PR