Revert of Add rudimentary shelf delegate mus unit test.

ash/mus/BUILD.gn

Index: ash/mus/BUILD.gn
diff --git a/ash/mus/BUILD.gn b/ash/mus/BUILD.gn
index 6b8a563c0088aa1add5405e0c06da01ad9c847c7..da25a6e595f84e998d6d028189020d732b7ba3a6 100644
--- a/ash/mus/BUILD.gn
+++ b/ash/mus/BUILD.gn
@@ -129,24 +129,3 @@
     "//ash/resources:ash_test_resources_200_percent",
   ]
 }
-
-source_set("unittests") {
-  testonly = true
-
-  sources = [
-    "shelf_delegate_mus_unittest.cc",
-  ]
-
-  deps = [
-    "//base",
-    "//components/mus/public/interfaces",
-    "//mash/shelf/public/interfaces",
-    "//mojo/public/cpp/bindings",
-    "//services/shell/public/cpp:shell_test_support",
-  ]
-
-  data_deps = [
-    "//mash/session",
-    ":mus",
-  ]
-}