LU-15796 build: require python2 for lustre-iokit deb

LU-15796 build: require python2 for lustre-iokit deb

Package python is not available on Ubuntu 22.04.
We can just require python2 in the control files.

Lustre-change: https://review.whamcloud.com/47164
Lustre-commit: TBD (from d46e59a541a4a2db73ccae95707f08d5d9c40ccd)

Test-Parameters: trivial clientdistro=ubuntu2004 \
testlist=obdfilter-survey

Change-Id: Id37c9babba31c575855238592cbac4ce5c9ee79a
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/47538
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>