MOBILE-4350 theme: Improve opacity of disabled items

Author: NoelDeMartin

src/addons/messages/tests/behat/snapshots/test-basic-usage-of-messages-in-app-view-recent-conversations-and-contacts_30.png

@@ -85,7 +85,9 @@ Feature: It navigates properly in pages with a split-view component.
     And I should find "Course 1" in the app
     And I should find "Course 2" in the app
     And I should find "Grade category C1" in the app
-    And the UI should match the snapshot
+
+    When I replace "/.*/" within "core-user-avatar .userinitials" with "M"
+    Then the UI should match the snapshot
 
     # Open C1 course grades
     When I press "Grade item C1" in the app

src/addons/mod/forum/tests/behat/snapshots/test-basic-usage-of-forum-activity-in-app-reply-a-post_14.png

@@ -1522,9 +1522,10 @@ html.ios div.fake-ion-item {
 
 // Disabled items.
 ion-item.item-disabled,
+ion-button.button-disabled,
 ion-item.item-interactive-disabled:not(.item-multiple-inputs) ion-label,
 ion-datetime.datetime-disabled {
-    opacity: .8 !important;
+    opacity: .65 !important;
 }
 
 // Hide details on items to align badges.