traffic_replay: Move 'traffic account' flag up a level

traffic_replay: Move 'traffic account' flag up a level

We create machine accounts for 2 different purposes:
1). For traffic generation, i.e. testing realistic network packets.
2). For generating a realistic large DB.

Unfortunately, we want to use different userAccountControl flags for
the 2 different cases. Commit 3338a3e257fa9f28 changed the flags used
for case #2, but this breaks case #1.

The problem is generate_users_and_groups() is called in both cases,
so we want the 'traffic account' flag passed into that function.
This ensures that the machine accounts get created with the appropriate
userAccountControl flags for the particular case you want to test.

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>