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

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

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

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Peers' do
+  describe 'GET /api/v1/instance/peers' do
+    around do |example|
+      original = Setting.peers_api_enabled
+      example.run
+      Setting.peers_api_enabled = original
+    end
+
+    context 'with peers api enabled' do
+      before { Setting.peers_api_enabled = true }
+
+      it 'returns http success' do
+        get api_v1_instance_peers_path
+
+        expect(response)
+          .to have_http_status(200)
+
+        expect(body_as_json)
+          .to be_an(Array)
+      end
+    end
+
+    context 'with peers api diabled' do
+      before { Setting.peers_api_enabled = false }
+
+      it 'returns http not found' do
+        get api_v1_instance_peers_path
+
+        expect(response)
+          .to have_http_status(404)
+      end
+    end
+  end
+end