refactor(query): simplify SQL parser error tracking

[KKould]

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

Summary

• Remove optional parser Backtrace state and the disabled-first, reparse-on-error flow
• Propagate the farthest active-branch error in a single parse
• Derive expected tokens from complete token dispatches and keep SQL parser errors deterministic
• Refresh parser error golden files for the new reporting model

Implementation

• Simplify Input and Error by removing Backtrace and interior mutability
• Merge same-position alternatives through the nom ParseError implementation
• Generate first-token candidates from try_dispatch arms for complete dispatches
• Guard speculative grammar branches with targeted lookahead and commit points
• Keep optional and repeated parser behavior aligned with direct parser errors rather than retaining discarded branch failures

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Validation:

• cargo fmt --all -- --check
• cargo test -p databend-common-ast
• cargo clippy -p databend-common-ast --all-targets -- -D warnings

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe:)

---

This change is 

[KKould]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: bbfb243f9d

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

[KKould]

@codex review

[chatgpt-codex-connector]

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.
Repo admins can enable using credits for code reviews in their settings.