[WIP] try simple scalar

[andylokandy]

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Summary

Summary about this PR

Closes #issue

[github-actions]

Pull request description must contain CLA like the following:

I hereby agree to the terms of the CLA available at: https://docs.databend.com/dev/policies/cla/

## Summary

Summary about this PR

- Close #issue

[github-actions]

This pull request's title is not fulfill the requirements. @andylokandy please update it 🙏.

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fix(query): fix group by string bug
  ^         ^---------------------^
  |         |
  |         +-> Summary in present tense.
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  +-------> Type: rfc, feat, fix, refactor, ci, docs, chore

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• rfc: this PR proposes a new RFC
• feat: this PR introduces a new feature to the codebase
• fix: this PR patches a bug in codebase
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[what-the-diff]

PR Summary

• Reduction of Clutter within the Code
  This PR thoroughly cleaned up the file src/query/expression/src/converts/meta/index_scalar.rs. We removed a number of redundant imports and unused types and structs, making this file easier to read and maintain.

• Simplified Data Structures
  We modified key data structures (IndexScalar, IndexColumn). This simplification was done through the elimination of several variant matches and type conversions that were found to be unnecessary for the function of the program.

• Removal of Unused Implementations
  Several unused implementations for conversion methods and operations like serialize, deserialize, eq, and PartialEq on IndexColumn have also been removed.

• Elimination of Extraneous Comments
  We have removed various unnecessary comments within the code to increase its readability.

The main aim of these changes is to make the code more maintainable and easier to work with by eliminating elements that are obsolete or unused.