Fix CaptivePortalLoginActivity probes to bypass Private DNS

Test: as follows
    - built
    - flashed
    - booted
    - runtest frameworks-net passes
    - manual testing on captive portal networks
Bug: 64133961
Bug: 77140445
Bug: 78548486

Merged-In: I749e8b5dba3b4af9ecb82bfb558c6f0e664531a4
Merged-In: Ic76d55861f385d1aecd360adda7f10142d083a47
Change-Id: Idbc4d90eeec257b36c5f374d61dea4600a0f8ebb
(cherry picked from commit 848d842a)