Fix ActiveJob::Base.queue_adapter error

When using the HaveEnqueuedMail matcher, the error message should not complain
about using "ActiveJob" matchers.

Author: Joel Lubrano

lib/rspec/rails/matchers/have_enqueued_mail.rb

@@ -201,7 +201,6 @@ def mail_job_message(job)
       #       MyMailer.welcome(user).deliver_later(queue: :urgent_mail)
       #     }.to have_enqueued_mail(MyMailer, :welcome).on_queue(:urgent_mail)
       def have_enqueued_mail(mailer_class, mail_method_name)
-        check_active_job_adapter
         HaveEnqueuedMail.new(mailer_class, mail_method_name)
       end
       alias_method :have_enqueued_email, :have_enqueued_mail

spec/rspec/rails/matchers/have_enqueued_mail_spec.rb

@@ -238,7 +238,7 @@ def email_with_optional_args(required_arg, optional_arg = nil); end
 
       expect {
         expect { TestMailer.test_email.deliver_later }.to have_enqueued_mail(TestMailer, :test_email)
-      }.to raise_error("To use ActiveJob matchers set `ActiveJob::Base.queue_adapter = :test`")
+      }.to raise_error("To use HaveEnqueuedMail matcher set `ActiveJob::Base.queue_adapter = :test`")
 
       ActiveJob::Base.queue_adapter = queue_adapter
     end