Statsd: ISOLATED_UID_CHANGED out of batterystats

Moves the calls to StatsLog.write for ISOLATED_UID_CHANGED to the
calling functions, rather than batterystatsimpl.

Bug: 80308558
Test: none?
Change-Id: I6fe389c536b2a456907c8a87fae61e9c3434004d
diff --git a/cmds/statsd/src/atoms.proto b/cmds/statsd/src/atoms.proto
index ab9c7e8..ca3786a 100644
--- a/cmds/statsd/src/atoms.proto
+++ b/cmds/statsd/src/atoms.proto
@@ -1484,6 +1484,7 @@
 message IsolatedUidChanged {
     // The host UID. Generally, we should attribute metrics from the isolated uid to the host uid.
     // NOTE: DO NOT annotate uid field in this atom. This atom is specially handled in statsd.
+    // This field is ignored when event == REMOVED.
     optional int32 parent_uid = 1;
 
     optional int32 isolated_uid = 2;