[roll] Roll fuchsia [build][sdk] Remove empty_fuchsia_sdk & empty_fuchsia_clang

They are unused after https://fxrev.dev/1253187.

Original-Bug: 401120294
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1255857
Original-Revision: acb5b5804bb610c3845fdeffc2aef8ba174d2fbd
GitOrigin-RevId: 4029e3b5862935736c05bec8b666f21dd7f3d1bd
Change-Id: I0cebc5b428456fc7fefa592bc0e53526ac4f8ea9
diff --git a/stem b/stem
index 1458968..b7c7cc9 100644
--- a/stem
+++ b/stem
@@ -8,7 +8,7 @@
              root=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="f98738569b90ac40e3fea45bc32eb864bd649621"
+             revision="acb5b5804bb610c3845fdeffc2aef8ba174d2fbd"
              />
   </imports>
 </manifest>