No need to use *magic mock_redis during test

This pull request try to remove the magic mock_redis. Test is failing so I would like to receive some insight:


```
Failures:

  1) When Sidekiq::Testing is enabled when set to :inline! when a job is set to run once in 10 minutes only allows 1 call per 10 minutes
     Failure/Error: expect(TestClass).to have_received(:run).with(1).twice
       <TestClass (class)> received :run with unexpected arguments
         expected: (1)
              got: (2)
     # ./spec/lib/sidekiq_testing_enabled_spec.rb:120:in `block (4 levels) in <top (required)>'
```