Properly detect Amazon Linux 2 final release platform version
Properly detect Amazon Linux 2 final release platform version

Make the release substring on RHEL platforms optional This fixes matching the new amazon linux which is entirely different
than literally every other RHEL like platform.

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

jaymzh/ohai,chef/ohai,higanworks/ohai,mattray/ohai,jaymzh/ohai,higanworks/ohai,mattray/ohai,chef/ohai