build/ops: refrain from installing/using lsb_release in install-deps.sh

build/ops: refrain from installing/using lsb_release in install-deps.sh

Unfortunately the mapping between release number and codename (which is only
relevant for Debian and Ubuntu btw) is not available from /etc/os-release.
In that one respect, lsb_release was "better".

However, when I weigh the advantages of obtaining that mapping from an external
tool, with the (substantial) risk that the external dependency might cause
trouble on one or more supported distros (to say nothing of the non- or
semi-/pseudo-supported ones), against the work involved in maintaining a
hard-coded mapping (negligible), the needle on my scale immediately swings
toward eliminating the dependency.

Also, I see this commit as part of the longer-term effort to completely expunge
lsb_release from our codebase. See git log --grep lsb_release.

For another example of an external distro-detection tool (albeit one that was
included in Python 2) gone awry, see http://tracker.ceph.com/issues/18163.

Signed-off-by: Nathan Cutler <ncutler@suse.com>
(cherry picked from commit 38508b41dc7f33a0b35e3633be3da1d2dae844dc)

Conflicts:
	install-deps.sh