Find and replace highlight sometimes jumps to the first item instead of next after replacing

[f1ames]

📝 Provide detailed reproduction steps (if any)

I'll start with videos since it illustrates this case nicely.

1st example works fine, and replace cycles nicely over words in order:

Screen.Recording.2024-07-02.at.11.43.35.mov

2nd and 3rd shows that highlight sometimes jumps to the first item:

Screen.Recording.2024-07-02.at.11.45.16.mov

Screen.Recording.2024-07-02.at.11.55.04.mov

Steps

As in 3rd video:

1. Got to editor instance with Find and Replace enabled, e.g. https://ckeditor.com/docs/ckeditor5/42.0.0/features/find-and-replace.html.
2. Use complex document, e.g. content from https://ckeditor.com/docs/ckeditor5/42.0.0/examples/builds/classic-editor.html.
3. Open Find and Replace dialog.
4. Type 'You' as "Find" and press "Find" button.
5. Navigate to 5th result.
6. Fill replace text and press replace.
7. Press replace again.

✔️ Expected result

Replace should cycle over items in order.

❌ Actual result

Sometimes highlight jumps to first item.

❓ Possible solution

Not sure, I was suspecting complex structure and first item in a block/paragraph but was not able to confirm that with quick testing.

📃 Other details

• Browser: Chrome
• OS: MacOS
• First affected CKEditor version: Not sure
• Installed CKEditor plugins: Find and replace

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[rmoustgaard]

This is simple to replicate without tracked changes:

• Go to https://ckeditor.com/ckeditor-5/demo/feature-rich/
• Replace all the text with "This doesn't work. This doesn't work. This doesn't work."
• Open Find and Replace, and Find the word "work".
• Click 'Next result' to skip the first occurrence.
• Replace the second occurrence with another word.
• Expected: Highlight/cursor moves to the third occurrence
• Actual: Cursor jumps back to the first occurrence.

[lkszzajac]

The issue is reproducible in blocks that contain 2+ occurrences of queried sequence. If there is only one occurrence, the selection is moved as expected.

• block with 1 occurrence:

one.occurrence.mov

• block with 2 occurrences:

two.occurrences.mov

[Mati365]

I proposed fix: #17292