Fix test-related issues (#17888)

* Remove obsolete RSS::Serializer test

Since #17828, RSS::Serializer no longer has specific code for deleted statuses,
but it is never called on deleted statuses anyway.

* Rename erroneously-named test files

* Fix failing test

* Fix test deprecation warnings

* Update CircleCI Ruby orb

1.4.0 has a bug that does not match all the test files due to incorrect
globbing

spec/services/delete_account_service_spec.rb

@@ -23,12 +23,10 @@ RSpec.describe DeleteAccountService, type: :service do
 
     let!(:account_note) { Fabricate(:account_note, account: account) }
 
-    subject do
-      -> { described_class.new.call(account) }
-    end
+    subject { described_class.new.call(account) }
 
     it 'deletes associated owned records' do
-      is_expected.to change {
+      expect { subject }.to change {
         [
           account.statuses,
           account.media_attachments,
@@ -43,7 +41,7 @@ RSpec.describe DeleteAccountService, type: :service do
     end
 
     it 'deletes associated target records' do
-      is_expected.to change {
+      expect { subject }.to change {
         [
           AccountPin.where(target_account: account),
         ].map(&:count)
@@ -51,7 +49,7 @@ RSpec.describe DeleteAccountService, type: :service do
     end
 
     it 'deletes associated target notifications' do
-      is_expected.to change {
+      expect { subject }.to change {
         [
           'poll', 'favourite', 'status', 'mention', 'follow'
         ].map { |type| Notification.where(type: type).count }
@@ -73,7 +71,7 @@ RSpec.describe DeleteAccountService, type: :service do
       let!(:local_follower) { Fabricate(:account) }
 
       it 'sends a delete actor activity to all known inboxes' do
-        subject.call
+        subject
         expect(a_request(:post, "https://alice.com/inbox")).to have_been_made.once
         expect(a_request(:post, "https://bob.com/inbox")).to have_been_made.once
       end
@@ -91,7 +89,7 @@ RSpec.describe DeleteAccountService, type: :service do
       let!(:local_follower) { Fabricate(:account) }
 
       it 'sends a reject follow to follower inboxes' do
-        subject.call
+        subject
         expect(a_request(:post, account.inbox_url)).to have_been_made.once
       end
     end