css: Set white-space: nowrap for channel dropdowns in org_settings.

This commit ensures that long channel names, including those
containing multiple words, are properly abbreviated in the channel
dropdown widgets in organization settings.

Follow up to commit:
9ae704510f org_settings: Correctly display long channel names,
which handled long single-word channel names.

web/styles/settings.css

@@ -858,6 +858,7 @@ input[type="checkbox"] {
         .decorated-channel-name {
             overflow-x: hidden;
             text-overflow: ellipsis;
+            white-space: nowrap;
         }
     }
 }