dumpstate: add network policy dumpsys to limited bugreports

This patch adds the output of "dumpsys netpolicy" to limited bugreports
used for example on ChromeOS ARC branches. This allows
NetworkPolicyListener to be removed from ArcNetworkStsrem Monitor.

Size and time running `adb bugreport` (average of 5 runs)
Before: 4767904kb / 0.3724s
After: 4950878.4kb / 0.3742

A sample output of added part:
https://paste.googleplex.com/5389883399208960#l=4

Bug: 353889237
Test: Flashed brya, generated arc bugreport with chrome://network#logs and checked that the content of dumpsys
netpolicy was there.
Flag: NONE Add logging to bug-reports

Change-Id: Ie0474c25ba6d934ab98da14a398672f8080f0cb1