use a singleton for ifaceIndexNameMap(IFACE_INDEX_NAME_MAP_PATH) am: 022b286f2b

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2924884

Change-Id: I2f32a41955ada556a91971e46346c9626ad74197
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>