Changing contextual trigger button background to background-color

Closes #3401990 The style is overriding core icons, if we change the line from background to background-color it solves the issue

styles/components/contextual_links.scss

@@ -27,7 +27,7 @@
     &,
     &:hover,
     &:focus {
-      background: var(--gin-bg-layer3);
+      background-color: var(--gin-bg-layer3);
       border: 1px solid var(--gin-border-color-layer2);
     }