Fix PO for material-suggest-input to get the correct overlay

PiperOrigin-RevId: 186668574

Author: Googler

lib/material_input/material_auto_suggest_input.html

@@ -56,7 +56,7 @@
 <material-popup
     #popup
     trackLayoutChanges
-    class="{{popupShadowCssClass}}"
+    class="selections {{popupShadowCssClass}}"
     [autoDismiss]="autoDismiss"
     [enforceSpaceConstraints]="enforceSpaceConstraints"
     [constrainToViewport]="constrainToViewport"