Follow Conversation: Fix cases where the follow button is missing

[dvdchr]

Refs pbArwn-3hB-p2#comment-4533

This fixes the case where the Follow button is missing due to the Post object not being available initially but is not refreshed after the Post object is obtained.

To test

Comment threads from Notifications

• Go to Notifications.
• Select any comment notification.
• Tap on the notification header to go to the comment threads.
• 🔍 Verify that the Follow button appears after the loading completes.

Comment threads from Site Comments

• Go to My Sites > Comments.
• Select any reply comment.
• Tap on the comment header to go to the comment threads.
• 🔍 Verify that the Follow button appears after the loading completes.

Regression Notes

1. Potential unintended areas of impact
   Should be none.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manually tested to ensure that it is working properly.

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.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

	Warnings
⚠️	This PR is assigned to a milestone which is closing in less than 4 days Please, make sure to get it merged by then or assign it to a later expiring milestone

Generated by 🚫 dangerJS

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[ScoutHarris]

✅ Comment threads from Notifications
✅ Comment threads from Site Comments