Revert "Trigger iid logic from GitHub importer for issues."

This reverts commit b78a69b0.

lib/gitlab/github_import/importer/issue_importer.rb

@@ -57,11 +57,7 @@ module Gitlab
             updated_at: issue.updated_at
           }
 
-          insert_and_return_id(attributes, project.issues).tap do |id|
-            # We use .insert_and_return_id which effectively disables all callbacks.
-            # Trigger iid logic here to make sure we track internal id values consistently.
-            project.issues.find(id).ensure_project_iid!
-          end
+          insert_and_return_id(attributes, project.issues)
         rescue ActiveRecord::InvalidForeignKey
           # It's possible the project has been deleted since scheduling this
           # job. In this case we'll just skip creating the issue.

spec/lib/gitlab/github_import/importer/issue_importer_spec.rb

@@ -78,11 +78,6 @@ describe Gitlab::GithubImport::Importer::IssueImporter, :clean_gitlab_redis_cach
         .to receive(:id_for)
         .with(issue)
         .and_return(milestone.id)
-
-      allow(importer.user_finder)
-        .to receive(:author_id_for)
-        .with(issue)
-        .and_return([user.id, true])
     end
 
     context 'when the issue author could be found' do
@@ -177,23 +172,6 @@ describe Gitlab::GithubImport::Importer::IssueImporter, :clean_gitlab_redis_cach
 
       expect(importer.create_issue).to be_a_kind_of(Numeric)
     end
-
-    it 'triggers internal_id functionality to track greatest iids' do
-      allow(importer.user_finder)
-        .to receive(:author_id_for)
-        .with(issue)
-        .and_return([user.id, true])
-
-      issue = build_stubbed(:issue, project: project)
-      allow(importer)
-        .to receive(:insert_and_return_id)
-        .and_return(issue.id)
-      allow(project.issues).to receive(:find).with(issue.id).and_return(issue)
-
-      expect(issue).to receive(:ensure_project_iid!)
-
-      importer.create_issue
-    end
   end
 
   describe '#create_assignees' do