apparmor: relax the restrictions on setting rlimits

Instead of limiting the setting of the processes limits to current,
relax this to tasks confined by the same profile, as the apparmor
controls for rlimits are at a profile level granularity.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>