Allow operators to set haproxy socket to admin level.
This is done via the flag haproxy_socket_level_admin which
is set to "no" by default.

Closes-Bug: 1960215

Signed-off-by: Imran Hussain <ih@imranh.co.uk>
Change-Id: Ia0da89288d68f5803ace1934c013053f12343195