LU-13969 tests: Updates to lustre-release yaml.sh

LU-13969 tests: Updates to lustre-release yaml.sh

Updated output of release() function to standarize node.yml
file os_distribution parameter. Changes as follows:

RHEL   - use redhat-release first and os-release as backup
         as the latter may not include the full version
         (major/minor)
CENTOS - use centos-release first and os-release as backup,
         same as RHEL
SUSE   - use os-release instead of suse-release as the latter
         is deprecated
UBUNTU - use os-release

Removed parsing system-release and *-release as neither
option correctly outputs desired info

Removed "lustre_" references in node.yml file attributes,
the default in Maloo is to look for non-lustre prefixes
first.

Lustre-commit: f90199b104984da5f2157e39a286d433b725ed57
Lustre-change: https://review.whamcloud.com/39952

Change-Id: Ia011f944aae53f31fcd3a539e846ea5aba7ec7c4
Signed-off-by: Lee Ochoa <lochoa@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/40402
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>