[CORL-3165]: only notify on approval when comment previously pending

[kabeaty]

What does this PR do?

This checks that the previous status of the comment was a PENDING_STATUS (premod or system withheld) and only creates a notification when a comment is approved in this case.

These changes will impact:

• [x] commenters
• [x] moderators
• [ ] admins
• [ ] developers

What changes to the GraphQL/Database Schema does this PR introduce?

none

Does this PR introduce any new environment variables or feature flags?

no

If any indexes were added, were they added to INDEXES.md?

n/a

How do I test this PR?

Create pending comments as a user (put the user on premod, for example). As another user, approve these comments. See that you get the expected notification of approval.

Report a user's comment. Then approve that comment as another user. See that there is no notification.

Create a comment with a suspect word. Then approve that comment as another user. See that there is no notification.

Were any tests migrated to React Testing Library?

How do we deploy this PR?

[netlify[bot]]

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