[roll] Roll fuchsia [omaha-client] Send realm id to Omaha.

This is available in vbmeta under the key 'ota_realm'.

Also refactored how we read from vbmeta in various places.

Original-Fixed: 98971
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/673703
Original-Revision: 7f109f09793278d335786243007a0b423f6f6513
GitOrigin-RevId: 9c81619c848d034e05b84551571440044d14a2ff
Change-Id: I93ba4f273a29f135fe9e8da34d7ef7fa7f0b917e
diff --git a/stem b/stem
index b6b106f..e304d4a 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="0425bee388e4e934f7ea2c20059f7a68ef9b4f7a"/>
+             revision="7f109f09793278d335786243007a0b423f6f6513"/>
   </projects>
   <hooks>
     <hook name="install-environment"