Enable cleartext for captive portal apps

When a user attempts to visit a captive portal the Activity will attempt
to load http://connectivitycheck.gstatic.com/generate_204 and a
walled-garden will typically intercept this and respond with a 302
redirect to a sign-in flow.

The new default of disabling cleartext unless explicitly enabled breaks
captive portal operation. This change enables cleartext for the two
applications that contain a CaptivePortalLoginActivity.

Clean cherry-pick of ag/3750960

Bug: 75279991
Test: Manually associated with captive portals.
Exempt-From-Owner-Approval: Already approved by owner on pi-dev.
Change-Id: Ib9ea7a8a2aa72b8305fa7044df0e369a57d33953
Merged-In: Ie38d6ce6f54336db2f4672746dc7385e0a7979fb
Merged-In: I742bf6be74a9e6953d0a779bdab0c25cf32aa740