Merge "Revert "Return the registry in registerNetworkAgent."" into main am: 82c551e08e

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3535263

Change-Id: I55bebcf99fef97c4d2d5d6a9b0ad680396586db8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>