[bug fix] Fix scope issue

[dturn]

What are you trying to accomplish with this PR?
Fix a bug

Traceback (most recent call last):
	10: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/concurrency.rb:13:in `block (2 levels) in split_across_threads'
	 9: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/concurrency.rb:13:in `each'
	 8: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/resource_watcher.rb:56:in `block in sync_resources'
	 7: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/kubernetes_resource/pod.rb:31:in `sync'
	 6: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/kubernetes_resource.rb:173:in `sync'
	 5: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/resource_cache.rb:18:in `get_instance'
	 4: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/resource_cache.rb:46:in `use_or_populate_cache'
	 3: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/resource_cache.rb:46:in `synchronize'
	 2: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/resource_cache.rb:48:in `block in use_or_populate_cache'
	 1: from /usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/resource_cache.rb:54:in `fetch_by_kind'
/usr/lib/ruby-shopify/ruby-shopify-2.6.4/lib/ruby/gems/2.6.0/gems/kubernetes-deploy-0.31.0/lib/krane/task_config.rb:14:in `global_kinds': uninitialized constant Krane::TaskConfig::ClusterResourceDiscovery (NameError)

How is this accomplished?
More strictly scope a class

What could go wrong?
We have test coverage on that line, I don't actually understand the cause, we should figure out how to reproduce it before merging.

[timothysmith0609]

Assuming you've tested this irl

[dturn]

The reason this doesn't impact Krane run is that krane cli pulls in all of krane via https://github.com/Shopify/kubernetes-deploy/blob/master/lib/krane/cli/krane.rb#L3. We (in a subsequent PR) need to change that to be krane/common