[nearby] Sync discoveryTimestamp field name am: 64e14583cc am: 704ca5c767

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2871219

Change-Id: I75d8f9c9aad7f5feac6c90878c0d5545519a8460
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>