[DeviceSync v2] Revise v2 DeviceSync network traffic annotations

Populate "sender" and "trigger" fields of the BatchGetFeatureStatuses
network traffic annotation, specifying where and when
BatchGetFeatureStatuses API calls are made.

Change sender from "CryptAuth V2 Device Manager" to "CryptAuth Device
Syncer".

Bug: 953087, 951969
Change-Id: I1e2c1aacc12707532af28d9ec365bc8c5661cc7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1682722
Commit-Queue: Josh Nohle <nohle@chromium.org>
Auto-Submit: Josh Nohle <nohle@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#675375}