Remove explicit width statements from ULS menu widths

These seem to be more harmful than useful. On small screen the menu width gets too narrow, and on large screens the menu width gets too wide. The min-widths are sufficient.

Related to https://phabricator.wikimedia.org/T276255

css/jquery.uls.css

@@ -21,12 +21,10 @@
 
 .uls-wide {
 	min-width: 715px;
-	width: 45%;
 }
 
 .uls-medium {
 	min-width: 360px;
-	width: 30%;
 }
 
 /* Override the grid */
@@ -36,7 +34,6 @@
 
 .uls-narrow {
 	min-width: 180px;
-	width: 20%;
 }
 
 /* Override the grid */