Chore(deps):Removing non-existent dependency

[Reetika2509]

Summary

This pull request refactors the VelaQL service implementation to remove the dependency on the unavailable github.com/kubevela/workflow/pkg/cue/packages package and the GetPackageDiscover() method. These changes ensure compatibility with the latest version of the KubeVela workflow module and resolve related build errors.

Key Changes

• Removed the import of github.com/kubevela/workflow/pkg/cue/packages from affected files.
• Refactored the velaQLServiceImpl struct to use an empty struct for the pd field, eliminating the need for PackageDiscover.
• Updated the NewVelaQLService constructor to initialize the empty struct.
• Fixed error handling for the UnmarshalTo method in the QueryView function to follow Go best practices.
• Cleaned up all references to the removed dependency and method.

Impact

• Build Stability: Resolves build errors caused by missing packages in the latest KubeVela workflow module.
• Code Maintainability: Reduces reliance on upstream dependencies, improving maintainability and future-proofing the service.
• No API Changes: Does not alter the external API or user-facing functionality.