fix: unread indicator label presence in message list

[khushal87]

The PR is responsible for fixing the current unread indicator pill visibility on the Message List.

• When you send a lot of messages post the viewable area, the indicator appeared which was buggy. This is now fixed.
• When you send a single long message in the message list that is more than the visible area the indicator appeared. It is fixed as well.
• When you are somewhere above in the message list, when you scroll to bottom, you would expect to see the unread messages label in the message list on top of the first unread received message. This is fixed as well.

Linear issue - https://linear.app/stream/issue/RN-158/investigate-faulty-appearance-of-unread-indicator-label-in-message

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
js_bundle_size	467 KB	467 KB	0 B	🟢

[stream-ci-bot]

🎉 This PR is included in version 6.7.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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