Fix flaky test ResolverTest.BrokenEdns

The test becomes flaky because of aosp/973195. The testing TLS
server have to stop in both OFF and OPPORTUNISTIC_UDP cases, or
there would be a timing issue in cuttlefish.

The test time is influenced accordingly, and now it takes about 3300ms.

Bug: 134372242
Test: ran 1000 times in cuttlefish
      resolv_integration_test --gtest_repeat=1000 --gtest_filter="ResolverTest.BrokenEdns"
Change-Id: I385149a5a0c372664244746db17f5e38b49c5699