Switch: not display outline when focused (#12771)

packages/theme-chalk/src/switch.scss

@@ -49,9 +49,6 @@
     height: 0;
     opacity: 0;
     margin: 0;
-    &:focus ~ .el-switch__core {
-      outline: 1px solid $--color-primary;
-    }
   }
 
   @include e(core) {