[5.0] installation rtl fixes (#41877)

There are two competing and conflicting declarations for the `j-install-step-header span`
This is the css that puts the space between the icon and the header

Note that the entire RTL css is incorrect but that is for another pr and another time. This PR is only to produce valid css without duplicate classes

installation/template/scss/template-rtl.scss

@@ -31,8 +31,8 @@ textarea.noResize {
 
 .j-install-step-header {
   span {
-    margin-right: 5px;
-    margin-left: auto;
+    margin-right: auto;
+    margin-left: 5px;
   }
 }
 
@@ -80,11 +80,6 @@ textarea.noResize {
   display: inline;
 }
 
-.j-install-step-header span {
-  margin-right: auto;
-  margin-left: 5px;
-}
-
 #jform_db_prefix {
   text-align: right;
   direction: ltr;