Remove services.net JAR dependency

Test: as follows
    - built, flashed, booted
    - runtest frameworks-net passes
    - captive portal interaction works as expected in Private DNS
      strict mode
Bug: 64133961
Bug: 72345192
Bug: 73872000
Bug: 78548486
Change-Id: Ia2ab2fb15e7898d99d30da20699e0bbd7a5a0964