[roll] Roll fuchsia [netconform] Explicitly tell ffx symbolizer path

Network conformance tests are failing in CI due to `ffx log` not finding
the SDK (which it needs for the symbolizer tool). Add in-tree test
coverage for this and add an explicit dependency on the symbolizer tool
and its SDK metadata via populating our own SDK manifest for our
isolated FFX instance.

Test: conformance_emulator_test
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/897258
Original-Revision: e8fe283678003c46e02d85487b281dd54e37d748
GitOrigin-RevId: dc7e9bf4c686e8f02559c48ee7509c62a307ec33
Change-Id: I58bc177f86e2206641eec268ee175c1ad7fdf6e4
diff --git a/stem b/stem
index 9430549..b7df61a 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="7014439c4f01b1dd9e1bd2184eda13fa633a0b52"/>
+             revision="e8fe283678003c46e02d85487b281dd54e37d748"/>
   </projects>
   <hooks>
     <hook name="install-environment"