docs: Remove automated List splitting and merging test

This was automated in WordPress/gutenberg#45048.

test-cases/gutenberg/writing-flow/readme.md

@@ -28,7 +28,6 @@
 - [ ] [TC005](https://github.com/wordpress-mobile/test-cases/blob/trunk/test-cases/gutenberg/writing-flow/splitting-merging.md#tc005) - Merge multiple blocks
   - [ ] Paragraph
   - [ ] Heading
-- [ ] [TC006](https://github.com/wordpress-mobile/test-cases/blob/trunk/test-cases/gutenberg/writing-flow/splitting-merging.md#tc006) - Splitting/merge list block
 #### Undo / Redo - Test Cases
 - [ ] [TC001](https://github.com/wordpress-mobile/test-cases/blob/trunk/test-cases/gutenberg/writing-flow/undo-redo.md#tc001) - Undo/redo block actions
 - [ ] [TC002](https://github.com/wordpress-mobile/test-cases/blob/trunk/test-cases/gutenberg/writing-flow/undo-redo.md#tc002) - Undo/redo text

test-cases/gutenberg/writing-flow/splitting-merging.md

@@ -75,20 +75,3 @@ Start from an empty post.
 - Press enter two times to create an empty block in between 
 - Press back two times to merge everything again.
 - Check that the blocks were merged.
-
-
-##### TC006
-
-**Splitting/merge list block**
-
-- Write some items on a list block
-- Put the caret by the half of them (at the end of the item) and press Enter to create a new item.
-- Press Enter again to split the block into two, with an empty paragraph block in the middle. The paragraph block at the middle should be focused.
-- Write something on that newly created paragraph block.
-- Move the cursor to the beginning of the paragraph block
-- Press delete to merge the paragraph block with the upper list block.
-- Check that the new word should be a new list item.
-- Move the caret to the beginning of the second list block.
-- Press delete once to merge it back into the first list block.
-- Check that everything was merged and there’s just one list block.
-