Fix the setting image contrast ratio of the settings_button is too low.

Bug: 149269156
Test: Manual test by accessibility scanner
Change-Id: Ie5e5283fc54debe15c6e12575a1db04ffa154635

src/com/android/settings/accessibility/ShortcutPreference.java

@@ -53,7 +53,7 @@ public class ShortcutPreference extends Preference {
     }
     private OnClickListener mListener = null;
 
-    private static final float DISABLED_ALPHA = 0.5f;
+    private static final float DISABLED_ALPHA = 0.77f;
     private static final float ENABLED_ALPHA = 1.0f;
     private int mSettingsVisibility = View.VISIBLE;
     private boolean mAutoEnabledSettings;