Using incorrect namespace while fetching drafts from Pipelines app

We hardcode `default` namespace while fetching drafts in the list view. https://github.com/cdapio/cdap/blob/develop/cdap-ui/app/cdap/components/PipelineList/DraftPipelineView/store/ActionCreator.ts#L52

This is incorrect and will cause users to not be able to access drafts in their custom namespace. This only happens in custom namespaces.

As a workaround,

• Navigate to http executor (Admin -> Configuration -> Make http call),

• Copy paste namespaces/system/apps/pipeline/services/studio/methods/v1/contexts/<namespace>/drafts
  in the path and replace the <namespace> with their own namespace.

• The backend should return a list of drafts with name and id

• Grab the id and navigate to this url

• After this the user should be able to see their draft.