Child blocks are displayed in the block inserter and block visibility doesn't work

[t-hamano]

What problem does this address?

I found two issues in the trunk:

• Child blocks that have a specific parent, such as the List Item, are displayed. When you click on the block, it will say "Block "{blockName}" can't be inserted.". (This may be a new specification)
• "Manage block visibility" doesn't work.

I used git bisect and it looks like this issue occurred in #65490.

https://github.com/user-attachments/assets/e9b761f6-79a2-4ab9-bde3-86b031d5e755

cc @youknowriad @andrewserong @jorgefilipecosta

[youknowriad]

Thanks for catching the bug and creating the issue. It seems the new behavior to "compute insertion point" on the fly should only apply to specific conditions, not all the conditions of when a block is visible or not.

So it's like we need two different kind of selectors:

• Can insert block
• Is block visible

I'll explore something.

[youknowriad]

We should have e2e tests about the "manage block visibility" thing