libdm: Redact keys from dm-crypt targets when calling GetTable. am: c434d801d6 am: 8dce05a18e am: 47bfad8f3c

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/29655996

Change-Id: Ia37bbdb92f5746eec3146e52d434afab376dd210
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>