assistant_context_editor: Fix copy paste regression (#31882)

Closes #31166

Release Notes:

- Fixed an issue where copying and pasting an assistant response in text
threads would result in duplicate text
6d99c12796Bennet Bo Fenner committed on 6/2/2025, 9:52:47 AM· committed by GitHubparent8fb7fa9
3 files changedLine totals unavailable