Converting a just created Reusable Block to Regular Blocks inserts a 'Reusable Template' block into a post

[talldan]

Describe the bug
When converting a just created Reusable Block (that has multiple blocks) into Regular Blocks, a wrapping 'Reusable Template' block is inserted into the post. This wrapping block seems to have a template lock and is hard to delete (no block settings menu and is not properly selectable).

To reproduce
Steps to reproduce the behavior:

1. Create two paragraph blocks with any text content (paragraphs are easiest, but any block type should have this issue)
2. Select the two paragraphs and create a reusable block from them
3. Convert this reusable block to regular blocks
4. Observe that the blocks are wrapped in a 'Reusable Template' block.

Expected behavior
The blocks are returned back to their original state.

Screenshots

Additional context

• Inserting other instances of the reusable block and converting to regular blocks works fine.
• Tested in Chrome
• Discovered in master at e8bc32112d1f4606009da1d7e46deeb7ab873378

[talldan]

Fixed by #14367