Test: Clean up some hard-coded flags in resolv_integaration_test

This change moves the hard-coded flags from resolv_integration_test.cpp
to the resolv_test_utils.h. There are no logic changes.

Bug: 271405311
Test: resolv_integration_test
Change-Id: I89f2fa45e7bf4e59476181fea4794f2601a2d1eb