Ignore some ConnectivityManagerTest CTS tests that can't be run in the instant app mode

1. testIsPrivateDnsBroken: It requires the
   permission:android.permission.WRITE_SECURE_SETTINGS. But the
   WRITE_SECURE_SETTINGS permission can't be granted to instant
   apps.
2. testSetOemNetworkPreferenceForTestOnlyPref: Instant apps can't
   create test networks.
3. testSetOemNetworkPreferenceForTestPref: Instant apps can't
   create test networks.

Bug: 191678254
Bug: 191680108
Test: atest android.net.cts.ConnectivityManagerTest --instant
      atest CtsNetTestCasesLatestSdk:ConnectivityManagerTest --instant
Original-Change: https://android-review.googlesource.com/1743373
Merged-In: Ice43bcf7a1dc34f4a54fefba7f408767f0a4341e
Change-Id: Ice43bcf7a1dc34f4a54fefba7f408767f0a4341e
1 file changed