Add a flag dot_keep_unusable_xport_sec am: 9fc1b07c

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2101596



Change-Id: I67b9c305856fed19b3d993590678e35ba6e8905d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>