Bug Description

As reported in #3259:

See #3259 (comment) for where this might be happening.

Expected Behaviour

Pasting arbitrary text should create a new text block with correct height

Steps to reproduce

1. Copy text from somewhere
2. Click on story page
3. Paste via keyboard
4. Notice how newly added text block does not update its height

Screenshots

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Acceptance criteria

• Pasting arbitrary text should create a new text block with correct height

Implementation brief

• Update maybeUpdateBlockDimensions so it correctly handles pasted blocks

QA testing instructions

1. Copy text from somewhere
2. Click on story page
3. Paste via keyboard ( CTRL + V)
4. Verify height of text block is the height of the text.

Demo

• https://youtu.be/X8i0Tb71QLc

Changelog entry

• Improve calculating block dimensions when pasting text