Refactor `met.process` and `dbfiles`

[Sweetdevil144]

Description

• Optimized the standardization process by combining the two loops and improving efficiency.
• Added return statement where we intended to return but didn't implement

Motivation and Context

Removed the redundant loop that iterated over standardize_result to update ready.id. Instead, ready.id is now directly assigned the values from the current iteration's standardize_result if is_standardized is TRUE every time we perform a standardization.

For now, I've commented out the previous changes and will remove them once the current changes are approved.

Review Time Estimate

• [ ] Immediately
• [ ] Within one week
• [x] When possible

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My change requires a change to the documentation.
• [ ] My name is in the list of CITATION.cff
• [ ] I have updated the CHANGELOG.md.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.