fix(select): open method triggered twice on click

Fixes the `open` method being triggered both by a click handler on the select trigger and the `onContainerClick` from the `MatFormField` integration.

Author: crisbeto

src/lib/select/select.html

@@ -1,7 +1,6 @@
 <div cdk-overlay-origin
      class="mat-select-trigger"
      aria-hidden="true"
-     (click)="toggle()"
      #origin="cdkOverlayOrigin"
      #trigger>
   <div class="mat-select-value">