metricsd: Removing brillo::Any from weaved's public APIs

Weaved replaces brillo::Any with base::Value in its client library,
so need to update clients.

Also this removes last D-Bus dependencies from metrics_collector.

BUG: 26558300
Change-Id: I82d571d7e2bd17347daeb1b70f48ec05378894f0
diff --git a/metricsd/metricsd.rc b/metricsd/metricsd.rc
index 825c87f..3d3e695 100644
--- a/metricsd/metricsd.rc
+++ b/metricsd/metricsd.rc
@@ -6,4 +6,4 @@
 service metricsd /system/bin/metricsd --foreground --logtosyslog
     class late_start
     user metricsd
-    group system dbus inet
+    group system inet