Convert /instances/* controller specs to request specs (#27988)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

spec/requests/api/v1/instances/extended_descriptions_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Extended Descriptions' do
+  describe 'GET /api/v1/instance/extended_description' do
+    it 'returns http success' do
+      get api_v1_instance_extended_description_path
+
+      expect(response)
+        .to have_http_status(200)
+
+      expect(body_as_json)
+        .to be_present
+        .and include(:content)
+    end
+  end
+end