remove redundant course import code

this code turns out to have been redundant
ever since this was merged in 2018:
https://gerrit.instructure.com/c/canvas-lms/+/158759/3/app/models/importers/wiki_page_importer.rb#111

so it can be removed and the course copy wiki specs still pass

test plan:
 - course copy specs pass

flag=none
refs CANVAS-N7CV

Change-Id: If694a0b1975c266cccfa663798ee33fce750b6a4
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/353069
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Mysti Lilla <mysti@instructure.com>
QA-Review: Jeremy Stanley <jeremy@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>

app/models/importers/course_content_importer.rb

@@ -189,16 +189,6 @@ module Importers
           Importers::BlueprintSettingsImporter.process_migration(data, migration)
         end
 
-        # be very explicit about draft state courses, but be liberal toward legacy courses
-        if course.wiki.has_no_front_page &&
-           migration.for_course_copy? &&
-           !migration.for_master_course_import? &&
-           (source = migration.source_course || Course.where(id: migration.migration_settings[:source_course_id]).first)
-          mig_id = migration.content_export.create_key(source.wiki.front_page)
-          if (new_front_page = course.wiki_pages.where(migration_id: mig_id).first)
-            course.wiki.set_front_page_url!(new_front_page.url)
-          end
-        end
         front_page = course.wiki.front_page
         course.wiki.unset_front_page! if front_page.nil? || front_page.new_record?
 

spec/models/content_migration/course_copy_spec.rb

@@ -1362,6 +1362,7 @@ describe ContentMigration do
         Timecop.travel(1.minute.from_now) do
           expect { run_course_copy }.not_to change(ContentExport, :count)
           expect { JSON.parse(@cm.reload.exported_attachment.open) }.not_to raise_error
+
           expect(@copy_to.wiki_pages.where(title: "one")).to exist
         end
       end