Include vcn_management in connectivity bugreports.

VCN is a new networking feature for carriers in Android S, so we need to
include this info in the BRs that carriers can collect.

vcn_management is already dumped in full BRs when all running services
are dumped.

Bug: 187870480
Test: adb shell am bug-report --telephony (inspect content)
Change-Id: I817b75b4be9b398ca605e033e129acef1c1420ea