Re-enable `COMMENT_FIELD` buf lint check

[amaury1093]

Summary

We disabled buf's COMMENT_FIELD, so that some proto fields don't need to have comments. Let's re-enable it.

Problem Definition

We disabled buf's COMMENT_FIELD, so that some proto fields don't need to have comments. But probably it's a good practice to over-comment, than to inadvertently forget some important fields.

ref: #9747 (review)

Proposal

• Remove ignoing COMMENT_FIELD in buf.yaml linter
• Audit proto files and add comments everywhere where it's missing
• Update ADR-044 concerning COMMENT_FIELD

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[tac0turtle]

we do this as a requirement for adding new proto messages, we can close the issue