Fixed Social Icons shape, and horizontal and vertical alignments (fixes

#28340) (#28448)

* Fixed Social Icons shape, and horizontal and vertical alignments (fixes #28340)

Original issue was that when adding Social Icons to a Navigation block, the icons would be oblong instead of circle. The icons only misshapened when size Small or Normal was selected. I also noticed that when a horizontal Nav block was added, the social icons wouldn't align horizontally, and in a vertical Nav block, the social icons wouldn't align vertically.

* removed padding-left:0.5em

packages/block-library/src/social-links/style.scss

@@ -21,7 +21,7 @@
 	.wp-social-link {
 		// This needs specificity to override some themes.
 		&.wp-social-link.wp-social-link {
-			margin: 4px 8px 4px 0;
+			margin: auto 8px auto 0;
 		}
 
 		// By setting the font size, we can scale icons and paddings consistently based on that.