Clean up and merge sbin.dhclient profile

[mckinney-subgraph]

• Merge our profile with the upstream Debian sbin.dhclient profile
  (Attached an example diff, needs a person to look at it more carefully instead of just applying it directly)
  apparmor_sbin-dhclient-debianvssgos.txt

• Clean up the "unconfined exec qualifier (ux)" warnings in our profile, first reported here
  Example:

Jul 17 22:08:56 subgraph apparmor[15635]: Starting AppArmor profiles:Warning from /etc/apparmor.d/sbin.dhclient (/etc/apparmor.d/sbin.dhclient line 45): Unconfined exec qualifier (ux) allows some dangerous environment variables to be passed to the unconfined process; 'man 5 apparmor.d' for details.
Jul 17 22:08:56 subgraph apparmor[15635]: Warning from /etc/apparmor.d/sbin.dhclient (/etc/apparmor.d/sbin.dhclient line 57): Unconfined exec qualifier (ux) allows some dangerous environment variables to be passed to the unconfined process; 'man 5 apparmor.d' for details.
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