Remove option to post single comment and submit review from pending comments

What does this MR do and why?

Removes the option to Add comment now to pending comments

• Removing the option on every single comment reduces cognitive overload; user selects same button every time without having to think twice
• Add comment now is still available during review when adding new comments

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MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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Related to Remove option to post single comment and submit... (!90287 - merged)

Related to ✨ Beautifying our UI: Create:Code Review ✨ (#364574 - closed)