Removed the shadower service for cadence-server

[agautam478]

What changed?
Removed the unused service for shadower.

From the code it looks like the idea was to run the shadower in the background of Cadence server and scanning the workflows in real time. The service pulls and scans the workflows but doesn't follow up on it.
The purpose of doing this is also unclear. Was it implemented to detect the non-determinism in real time for whatever workflows are running on the server?

What was the plan to monitor the outcome of this service?

Why?
The code is redundant and creates noise. Also, it doesn't look like it's serving any purpose. In future if we want to include a real time shadower we can probably utilize the CLI based solution for open source.

How did you test it?
Ran the integration tests.

Potential risks
NA

Release notes
NA

Documentation Changes
NA

[coveralls]

Pull Request Test Coverage Report for Build 018da3f3-2d5b-4670-9603-9056c857d7fb

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 65 unchanged lines in 11 files lost coverage.
• Overall coverage decreased (-0.02%) to 62.682%

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Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	2	88.56%
common/util.go	2	91.69%
service/frontend/api/handler.go	2	62.05%
service/matching/taskReader.go	2	84.88%
common/persistence/statsComputer.go	3	94.64%
service/matching/taskListManager.go	3	80.2%
common/archiver/filestore/historyArchiver.go	4	80.95%
common/task/fifo_task_scheduler.go	7	82.47%
service/frontend/wrappers/metered/metered.go	9	62.02%
common/persistence/sql/workflowStateMaps.go	12	83.62%

Totals
Change from base Build 018da1d5-6df2-44d7-b0ae-f78d4eeeb41f:	-0.02%
Covered Lines:	92338
Relevant Lines:	147312

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💛 - Coveralls