Update QS network logging string

If network logging is enabled on the work profile
by a profile owner, use the string 'Work profile
network activity is visible to your IT admin'

Bug: 183606908
Test: atest com.android.systemui.qs.QSSecurityFooterTest
      manual testing - enable network logging as a
      profile owner on a BYOD device and a corp-owned
      device. Verify correct string.
Change-Id: I7b6537ea5e7b906f49f353a92a8911df1fbae631