[roll] Roll fuchsia [idk][build] Only define "core" in the main build

Only define the "core" target in the main build for clarity.

Original-Bug: 347094435, 393154095
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1198648
Original-Revision: 3ba530b966553f05f673f37b0dd84d847fdd8969
GitOrigin-RevId: 03521055429bd040a3cb28500fc9b821589f045a
Change-Id: I788a0611b9a345e7400e7eccd8312f214e2ce08c
diff --git a/stem b/stem
index 5872399..3706760 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="2364f692097a7d4fe00f361b5c984f928ecdaea2"/>
+             revision="3ba530b966553f05f673f37b0dd84d847fdd8969"/>
   </projects>
   <hooks>
     <hook name="install-environment"