Generalize disabled nav links CSS rules (#38774)

Co-authored-by: Patrick H. Lauke <redux@splintered.co.uk>

Author: julien-deramond

scss/_nav.scss

@@ -44,7 +44,8 @@
   }
 
   // Disabled state lightens text
-  &.disabled {
+  &.disabled,
+  &:disabled {
     color: var(--#{$prefix}nav-link-disabled-color);
     pointer-events: none;
     cursor: default;
@@ -79,13 +80,6 @@
       isolation: isolate;
       border-color: var(--#{$prefix}nav-tabs-link-hover-border-color);
     }
-
-    &.disabled,
-    &:disabled {
-      color: var(--#{$prefix}nav-link-disabled-color);
-      background-color: transparent;
-      border-color: transparent;
-    }
   }
 
   .nav-link.active,
@@ -117,12 +111,6 @@
 
   .nav-link {
     @include border-radius(var(--#{$prefix}nav-pills-border-radius));
-
-    &:disabled {
-      color: var(--#{$prefix}nav-link-disabled-color);
-      background-color: transparent;
-      border-color: transparent;
-    }
   }
 
   .nav-link.active,