Use ic_action_open when icon is not given in RemoteAction

Fallback icon is used whenever there are more than one apps to handle
the intent.

Test: Install two browsers. Send a text message with url, observe
the new icon is shown.
Test: With just one browser, observe the icon is the app icon.

FIXES: 124038152

Change-Id: I6e3d78a48cc922c0ee43172f361c6b4a18b43d20