Fix test when the batch_size is 1

lib/gitlab/database/background_migration/batched_job.rb

@@ -112,7 +112,7 @@ def time_efficiency
         end
 
         def can_split?(exception)
-          attempts >= MAX_ATTEMPTS && TIMEOUT_EXCEPTIONS.include?(exception&.class) && batch_size > sub_batch_size && batch_size >= 2
+          attempts >= MAX_ATTEMPTS && TIMEOUT_EXCEPTIONS.include?(exception&.class) && batch_size > sub_batch_size && batch_size > 1
         end
 
         def split_and_retry!

spec/lib/gitlab/database/background_migration/batched_job_spec.rb

@@ -305,8 +305,8 @@
       it { expect(subject).to be_falsey }
     end
 
-    context 'when the batch_size is 1' do # rubocop:disable RSpec/RepeatedExampleGroupBody
-      let(:job) { create(:batched_background_migration_job, :failed, batch_size: 2, sub_batch_size: 4) }
+    context 'when the batch_size is 1' do
+      let(:job) { create(:batched_background_migration_job, :failed, batch_size: 1) }
       let(:exception) { ActiveRecord::StatementTimeout.new }
 
       it { expect(subject).to be_falsey }