Mahjong parent tile block selector doesn't use the same click space as other icons

[mapk]

Describe the bug
The new block parent selector's click space is not the same as other icons in the toolbar. When I hover over an icon, normally the click space is the whole square. In the case of the parent selector, it's not.

To reproduce
Steps to reproduce the behavior:

1. Create a Columns block
2. Hover over a block icon of a nested block inside the Columns block
3. When the parent block icon appears above begins to hover over that icon
4. Notice the click space is different

Expected behavior
I expect the click space to be the same.

Screenshots

Editor version (please complete the following information):

• WordPress version: 5.4
• Gutenberg version: 8.2

Desktop (please complete the following information):

• OS: Mac OS X
• Chrome