Block Editor: Ungroupable, non-reusable blocks show redundant block settings popover section

[aduth]

Possible regression of #19344 (cc @youknowriad, @jasmussen )

Steps to Reproduce:

1. Navigate to Posts > Add New
2. Insert Social Icons block
3. Click block settings
4. Observe undesirable blank section between "Duplicate" and "Remove block"

Suspected cause:

This section of the block settings normally contains "Add to Reusable blocks" and "Group" options, which leads me to think that we are not correctly omitting the section when a block is neither reusable nor groupable.

Example for paragraph block:

I note that this is a "possible regression of #19344", because I am not able to reproduce this in WordPress 5.4 Beta 3, but I can reproduce it in the latest master.

[gziolo]

It might be related to #20233. It has guard clause that checks fills before it renders the wrapper but it might be buggy.