[styles] Remove `margin` normalization already covered in 'normalize' module

Has been introduced before 'normalize' module, now it's time to remove
duplicated style property.

Change-Id: Idff74430655c29b67dfccf97a22f53caaee34155

resources/skins.vector.styles/SearchBox.less

@@ -75,8 +75,6 @@
 	right: @border-width-base;
 	min-width: @min-width-search-button;
 	width: @width-search-button;
-	// Support macOS Safari 14-: Remove `margin` weirdly set in user-agent stylesheet.
-	margin: 0;
 	border: 0;
 	padding: 0;
 	cursor: pointer;