[Flexible Layouts] The Remove Container (frame) button does work, but now it's available when there's only one frame

[unlikelyzero]

Summary

The Remove Container (frame) button does work, but now it's available when there's only one frame; clicking it in this context deletes any content in the container, but doesn't remove the container - because it can't, the FL must have at least one container. The UI should not make the remove button available when there's only one container.

Impact Check List

• Data loss or misrepresented data?
• Regression? Did this used to work or has it always been broken?
• Is there a workaround available?
• Does this impact a critical component?
• Is this just a visual bug with no functional impact?
• Does this block the execution of e2e tests?
• Does this have an impact on Performance?