Make the Geo OAuth application trusted by default

When a Geo secondary node is set up, we create a System
OAuth application, which is currently untrusted by
default.

This means every user that tries to login on a new
secondary will first receive this authorization popup.

Considering that Geo is actually "provided by GitLab",
the popup seems unnecessary, and we could set the
application as trusted by default.

ee/app/models/geo_node.rb

@@ -377,7 +377,12 @@ class GeoNode < ApplicationRecord
   def update_oauth_application!
     return unless uri
 
-    self.build_oauth_application if oauth_application.nil?
+    if oauth_application.nil?
+      self.build_oauth_application
+      self.oauth_application.trusted = true
+      self.oauth_application.confidential = true
+    end
+
     self.oauth_application.name = "Geo node: #{self.url}"
     self.oauth_application.redirect_uri = oauth_callback_url
   end

ee/spec/models/geo_node_spec.rb

@@ -156,17 +156,28 @@ RSpec.describe GeoNode, :request_store, :geo, type: :model do
             expect(node).to be_valid
 
             expect(node.oauth_application).to be_present
-            expect(node.oauth_application.redirect_uri).to eq(node.oauth_callback_url)
+            expect(node.oauth_application).to have_attributes(
+              confidential: true,
+              trusted: true,
+              redirect_uri: node.oauth_callback_url
+            )
           end
         end
 
-        it 'overwrites redirect_uri' do
+        it 'overwrites name, and redirect_uri attributes' do
+          node.oauth_application.name = 'Fake App'
+          node.oauth_application.confidential = false
+          node.oauth_application.trusted = false
           node.oauth_application.redirect_uri = 'http://wrong-callback-url'
           node.oauth_application.save!
 
           expect(node).to be_valid
-
-          expect(node.oauth_application.redirect_uri).to eq(node.oauth_callback_url)
+          expect(node.oauth_application).to have_attributes(
+            name: "Geo node: #{node.url}",
+            confidential: false,
+            trusted: false,
+            redirect_uri: node.oauth_callback_url
+          )
         end
       end