Specify index adapter so spec doesn't use null

spec/jobs/migrate_files_to_valkyrie_job_spec.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 require 'wings'
 
-RSpec.describe MigrateFilesToValkyrieJob, valkyrie_adapter: :freyja_adapter, perform_enqueued: [MigrateFilesToValkyrieJob] do
+RSpec.describe MigrateFilesToValkyrieJob, index_adapter: :solr_index, valkyrie_adapter: :freyja_adapter, perform_enqueued: [MigrateFilesToValkyrieJob] do
   let(:user)      { create(:user) }
   let(:content) { File.open(fixture_path + '/' + label) }
   let(:uploaded_file1) { build(:uploaded_file, file:) }
@@ -23,9 +23,6 @@
 
   before do
     allow(Hyrax.config).to receive(:valkyrie_transition?).and_return(true)
-    # allow(ActiveFedora::Base).to receive(:find).and_call_original
-    # allow(ActiveFedora::Base).to receive(:find).with(migrated_file_set.original_file.file_identifier.to_s).and_return(file_with_characterization)
-    # allow(File_Set).to receive(:find).with(fedora_file_set.id).and_return(fedora_file_set)
   end
 
   it "it migrates all derivatives along with a file" do