ext-2814 turn off border on "Press a key to select" floater

indra/newview/skins/default/xui/en/floater_select_key.xml

 <?xml version="1.0" encoding="utf-8" standalone="yes" ?>
 <floater
  legacy_header_height="18"
- border="true"
+ border="false"
  can_close="false"
  can_minimize="false"
  height="100"