Bug 1854557 - include fetch-content in startup-test sparse checkout r=aryx

Differential Revision: https://phabricator.services.mozilla.com/D188945

build/sparse-profiles/startup-test

@@ -0,0 +1,6 @@
+%include build/sparse-profiles/mozharness
+
+[include]
+# for fetch-content
+path:taskcluster/scripts/misc/
+

taskcluster/ci/startup-test/kind.yml

@@ -31,7 +31,7 @@ job-defaults:
     worker:
         max-run-time: 3600
     run:
-        sparse-profile: mozharness
+        sparse-profile: startup-test
     attributes:
         build_type: opt
     treeherder: