Fix edited timestamp updated when transforming / resolving comments

What does this MR do?

This MR fixes edited timestamp updated when transforming / resolving comments without data migration.

Closes #27311 (closed)

Migrations

rake db:migrate

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== 20210303053341 AddLastEditedAtAndLastEditedByIdToNotes: migrating ==========
-- add_column(:notes, :last_edited_at, :datetime_with_timezone)
   -> 0.0029s
== 20210303053341 AddLastEditedAtAndLastEditedByIdToNotes: migrated (0.0030s) =

rake db:rollback

WARNING: This version of GitLab depends on gitlab-shell 13.17.0, but you're running 13.15.0. Please update gitlab-shell.
== 20210303053341 AddLastEditedAtAndLastEditedByIdToNotes: reverting ==========
-- remove_column(:notes, :last_edited_at, :datetime_with_timezone)
   -> 0.0040s
== 20210303053341 AddLastEditedAtAndLastEditedByIdToNotes: reverted (0.0060s) =

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