[nearby] Sync discoveryTimestamp field name am: 64e14583cc

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

Change-Id: I08857e513a8785cc4dbfb07b90c582754381bde4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>