[e2e] Cleanup ermine_session_shell_test, finish.

Submit once https://fuchsia-review.googlesource.com/c/fuchsia/+/291493
has rolled.

First part of this change is
https://fuchsia-review.googlesource.com/c/topaz/+/290766

Change-Id: Ibe5216680b9c7f06bd4e34c808e178ee81edf3a2
diff --git a/packages/tests/BUILD.gn b/packages/tests/BUILD.gn
index a199754..5a96e2e 100644
--- a/packages/tests/BUILD.gn
+++ b/packages/tests/BUILD.gn
@@ -205,11 +205,3 @@
     "//topaz/tests/dart_fidl_benchmarks",
   ]
 }
-
-# TODO(mesch): Remove. Cf. topaz/shell/ermine/test/end_to_end/README.md
-group("end_to_end") {
-  testonly = true
-  public_deps = [
-    "//topaz/shell/ermine/test/end_to_end:test",
-  ]
-}