Remove support for MediaWiki <= 1.39

With release of MediaWiki 1.41 we no longer need to support MW 1.39

Bug: T355105
Change-Id: I7957ca8aefee168ef11bc20905abd9944faecd73

resources/css/ext.uls.displaysettings.less

@@ -5,8 +5,6 @@
 .uls-button-group {
 	display: inline-block;
 	position: relative;
-	// The 1px are needed to handle overflow in .cdx-button-group in 1.39
-	padding: 1px 0 0 1px;
 	left: -20px;
 }
 

resources/css/ext.uls.languagesettings.less

@@ -130,19 +130,16 @@
 	margin-left: 15px;
 }
 
-// This can be removed when 1.39 support is dropped.
-.uls-input-settings-inputmethods-list .cdx-radio__label,
-.checkbox.cdx-checkbox__label {
-	padding-left: ~'calc(1.25em + 8px)';
-}
-
 .uls-ui-languages p,
 .checkbox {
 	color: @color-subtle;
 	font-size: 10pt;
 }
 
-/* @todo: Amend to use Codex when 1.39 support is no longer needed. */
+/*
+ * @todo: ULS settings dialog uses buttons as tabs. Amend to use Tabs component
+ * from Codex when 1.39 support is no longer needed.
+ */
 #languagesettings-panels .uls-cdx-button-pressed {
 	background-color: @background-color-progressive--active;
 	color: @color-inverted;