Notifications: remove notification for deleted Comment

[ScoutHarris]

Ref: #17790, #18010 (review)

When a comment is deleted from My Site Comments, the corresponding notification is removed from the Notifications list. In split view, if the currently selected notification is removed, the first available notification is selected and displayed.

To test:

• In split view, go to Notifications.
• Select a Comment notification.
• Go to My Sites tab > Comments.
• Delete the comment for the selected notification.
• Return to Notifications.
• Verify:
  • The notification for the deleted comment is removed.
  • The first available notification is selected and the details are shown.
  • The table is responsive.
• Disable notificationCommentDetails.
• Repeat the steps above.

Regression Notes

1. Potential unintended areas of impact
   N/A

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   N/A

3. What automated tests I added (or what prevented me from doing so)
   N/A

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[wpmobilebot]

You can test the Jetpack changes on this Pull Request by downloading it from AppCenter here with build number: pr18028-f0ebd08. IPA is available here. If you need access to this, you can ask a maintainer to add you.

[wpmobilebot]

You can test the WordPress changes on this Pull Request by downloading it from AppCenter here with build number: pr18028-f0ebd08. IPA is available here. If you need access to this, you can ask a maintainer to add you.

[dvdchr]

Tested and everything works! LGTM!