Description

The Add block toolbar button does nothing in wirte mode or contentOnly mode, so lets' hide it.

Step-by-step reproduction instructions

• Open the site editor.
• Insert an Accordion block.
• Change into write mode.
• Select the Accordion block.

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure