[ENHANCEMENT] argilla: Remove attribute-like access

[frascuchon]

Description

This PR addresses discussion from PR #5026 and removes attribute-like access for record fields, vectors and metadata.

Type of change

(Please delete options that are not relevant. Remember to title the PR according to the type of change)

• New feature (non-breaking change which adds functionality)
• Refactor (change restructuring the codebase without changing functionality)
• Improvement (change adding some improvement to an existing functionality)

How Has This Been Tested

(Please describe the tests that you ran to verify your changes. And ideally, reference tests)

• Test A
• Test B

Checklist

• I added relevant documentation
• I followed the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[davidberenstein1957]

Looking good. Just check there are no doc updates required?

[frascuchon]

Looking good. Just check there are no doc updates required?

yes. I did. In docs we are using only dict-like access for metadata