Small change to recently submitted update for tasks 26663/26669.
As neutron config 'enable_new_agents' is now set to False,
agents other than the managed L3 and DHCP agents do not ever
get their admin_state_up set to True (though it is unclear if
the agents actually respect the admin_state_up setting). This
change sets all admin_state_up values to True on host enable
for all agents. On Host disable the admin_state_up is not changed
for agents other than L3 and DHCP.
Story: 2003857
Task: 29069
Change-Id: I2d6d426b9111361e109c00dbc3a23ece6cb2916f
Signed-off-by: Kevin Smith <kevin.smith@windriver.com>