Revert "Return the registry in registerNetworkAgent."

Revert submission 3535182

Reason for revert: <Droidmonitor created revert due to b/404070202.Will be verified through ABTD for standard investigation.>

Reverted changes: /q/submissionid:3535182

Change-Id: I2febd2ee7227d487d9cd69dcabd9c04f888fd2de
9 files changed