Drop tautological delete.id checks

Repo.delete always returns the struct it was given, so deleted.id
== original.id is trivially true. Thread deleted.id through the
trailing get_*! call instead, so the binding is load-bearing.

Refs #176

test/music_library/online_store_templates_test.exs

@@ -114,8 +114,7 @@ defmodule MusicLibrary.OnlineStoreTemplatesTest do
     test "deletes the template" do
       template = online_store_template()
       assert {:ok, deleted} = OnlineStoreTemplates.delete_template(template)
-      assert deleted.id == template.id
-      assert_raise Ecto.NoResultsError, fn -> OnlineStoreTemplates.get_template!(template.id) end
+      assert_raise Ecto.NoResultsError, fn -> OnlineStoreTemplates.get_template!(deleted.id) end
     end
   end
 

test/music_library/record_sets_test.exs

@@ -137,8 +137,7 @@ defmodule MusicLibrary.RecordSetsTest do
     test "deletes the record set" do
       set = record_set()
       assert {:ok, deleted} = RecordSets.delete_record_set(set)
-      assert deleted.id == set.id
-      assert_raise Ecto.NoResultsError, fn -> RecordSets.get_record_set!(set.id) end
+      assert_raise Ecto.NoResultsError, fn -> RecordSets.get_record_set!(deleted.id) end
     end
   end