Remove actor customizations

[laritakr]

Refs scientist-softserv#30
Actor changes dealing with nested indexing are obsolete with upgrade.
Ran specs locally for DEPENDENCIES_NEXT=1 with only the 10 known failures appearing.

Conditionally remove env.curation_concern.reindex_extent

• Custom actors use env.curation_concern.reindex_extent = "queue#{env.importing.id}" if env.importing in queued_nesting_indexer.rb and nested indexing is obsolete.
• Both of the overridden actors are there to bring in the importer flag in order to support the nested indexing. There is no harm in keeping but they can be deleted during the cleanup of App.rails_5_1?
• Jobs, Actors, and Indexers are all affected.
• Unsure if any searches will break due to removing nested indexing... if so, after testing, may need to change to graph searches.