Change for private space intro screen string changes

This includes below changes based on latest UX mocks
- Changes the strings and icon in the intro screen
- Updates the title in Auto advance screens

Recording link : b/326391690#comment4
Screenshots:
go/ss/9xbZP5Lp8j9yh6m.png
go/ss/pvKMNdgu6yt2Xtr.png

Bug: 326391690
Test: Manual, verify the strings are updated as in Mocks
Change-Id: I714919ac1f3d45fa0007395bd17cfb340874ed5a