[roll] Roll fuchsia [ffx][emu] Find an unused CID to use

Rather than just rely on the CID provided in the virtual device, we
instead find one dynamically at runtime.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1207226
Original-Revision: 45cecafb7009c23ba5a88a2438b3814f68fdc30a
GitOrigin-RevId: b54a887d30ba1ee852642541247b297d02d6d9be
Change-Id: I2dd66c2e56cf0f40e2c4c0aa7c044d84c9b1a559
diff --git a/stem b/stem
index 87209b5..cf52456 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="a6e227c8bdf30844c02da3457b9cae2271ad542c"/>
+             revision="45cecafb7009c23ba5a88a2438b3814f68fdc30a"/>
   </projects>
   <hooks>
     <hook name="install-environment"