LU-16183 test: sanity-hsm/70 should detect python

LU-16183 test: sanity-hsm/70 should detect python

Check for python2 and python3 explicitly, since the
generic python command does not exist in newer distros.

Test-Parameters: env=SLOW=yes,ENABLE_QUOTA=yes \
clientdistro=sles15sp3 testlist=sanity-hsm
Test-Parameters: env=SLOW=yes,ENABLE_QUOTA=yes \
clientdistro=el7.9 testlist=sanity-hsm

Change-Id: I35bbe15fd298341870ad4f1ab5976e82ccc84667
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/48737
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Charlie Olmstead <charlie@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>