Change Recommendation: Whole change is marked in red and not only the relevant parts

[MSoeb]

Describe the bug
If a change recommendation with several changes goes from the end of a paragraph to the next paragraph via a blank line, the difference is displayed incorrectly. Everything is displayed as a change instead of the correct places.

Original motion:

View of changes done:

View after change recommendation:

How to Reproduce
Steps to reproduce the behavior:

1. open meeting
2. open motions > create a motion with two paragraphs and separate them with an empty line.
3. create a change recommendation with start at last line of paragraph one to first line of the seocnd paragraph.
4. change a word in the last line, add at least three words in the empty line and change something in the first line.

Expected behavior
Changes made by a change recommendation should be displayed correctly. In specific case, only the affected sections should be marked in red or green, not the entire section, and it should be easy and clear to see which sections have been changed, i.e. deleted or added.

This issue is part of the Meta Diff issue. #2956