Decrement Redis Counter for Errored Sidekiq Jobs

[hkim3162]

In Sidekiq Instrument, ensure that in the rescue block of when a job errors that we continue to decrement the counter. When jobs are errored the enqueue increment never gets removed

• Adds a decrement to the redis count in an ensure block
• Adds Rubocop as a development dependency (not adding to CI at this time as there are quite a lot of issues)
• Adds additional rspecs that utilize both server and client middleware
• cleans up some code/unused tests

[SheffAtEnova]

Two more last bits in line with the rest of the feedback.