LU-13514 tests: remove upgrade images for conf-sanity

LU-13514 tests: remove upgrade images for conf-sanity

conf-sanity test 32a is hanging at a high rate.  We need to
explore if the issue involves old images are having problems
upgrading to the latest version of Lustre.

Test-Parameters: trivial
Test-Parameters: env=ONLY=32a,ONLY_REPEAT=20 fstype=ldiskfs testlist=conf-sanity
Test-Parameters: env=ONLY=32 fstype=zfs testlist=conf-sanity
Signed-off-by: James Nunez <jnunez@whamcloud.com>
Change-Id: I0ff1e9e1304192b1008551b82133d95a0010c86a
Reviewed-on: https://review.whamcloud.com/39109
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/40492
Reviewed-by: Oleg Drokin <green@whamcloud.com>