String update for screen recording

- Only show display name when more than 1 screen is available

   Android now supports recording external display. By default
   we show the device name along the "record screen" option,
   but we don't need to show it when no external display is connected

- Update the default string to match the new UI Mock

Test: CtsMediaProjectionTestCases
Test: SystemUIGoogleRobo2RNGTests
Bug: 362720120
Flag: EXEMPT Bug fix
Change-Id: I5986c9c3720d5e647389ad5fcc8dd62b41d32231