Color popovers: inconsistent styling

[jameskoster]

Here are the color palette, and custom color picker popovers:

As you can see, they both have different shadow styles, and the custom color popover has no border while the color palette one does. It would be nice to align the appearance:

The padding is slightly different too, so we might consider correcting that as well.

[mirka]

This should be pretty simple.

1. Wrap it with <DropdownContentWrapper paddingSize="none">.

2. Remove these style overrides:

   gutenberg/packages/components/src/color-palette/style.scss

   Lines 35 to 40 in 12b7960

   	overflow: visible;
   	box-shadow: 0 4px 4px rgba(0, 0, 0, 0.05);
   	border: none;
   	outline: none;
   	border-radius: $radius-block-ui;
   	padding: 0;