Resizing a table with column count changed by another user breaks the RTC

[Dumluregn]

📝 Provide detailed reproduction steps (if any)

1. Open an RTC demo with table column resize plugin loaded.
2. Join as a second user.
3. Resize a table and remove some columns.
4. Try to resize the table as a second user.

✔️ Expected result

Resizing the table should work normally for both users.

❌ Actual result

The user that didn't delete the columns gets errors while resizing.

❓ Possible solution

That happens because the table state is stored locally in the plugin (`cellIndexMap`) and not updated between the editor instances in RTC.

📃 Other details

• Browser: all
• OS: all
• First affected CKEditor version:
• Installed CKEditor plugins: table-column-resize

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[Dumluregn]

Solved with #12288.