[roll] Roll fuchsia [kernel][vm] Rename PrivatePagerCopy clone type

Rename PrivatePagerCopy to SnapshotAtLeastOnWrite.

Original-Bug: 34458
Run-All-Tests: true
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/879234
Original-Revision: c4af1b35b5f8f6229808184a3d839b89f911f5b1
GitOrigin-RevId: 910e2c9b0c0575254f68d1d12b3b04520bd224a4
Change-Id: Ic1a07ecdb6110e34e3f299de69bd816a5f32867a
diff --git a/stem b/stem
index c6a5cd7..891c208 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="8fec7b14534aec90c2bf6a12e370d8f0befa230a"/>
+             revision="c4af1b35b5f8f6229808184a3d839b89f911f5b1"/>
   </projects>
   <hooks>
     <hook name="install-environment"