Only update required instance CI template when the parameter is present

Changelog: fixed

app/controllers/admin/application_settings_controller.rb

@@ -208,7 +208,10 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
 
     params[:application_setting][:import_sources]&.delete("")
     params[:application_setting][:restricted_visibility_levels]&.delete("")
-    params[:application_setting][:required_instance_ci_template] = nil if params[:application_setting][:required_instance_ci_template].blank?
+
+    if params[:application_setting].key?(:required_instance_ci_template)
+      params[:application_setting][:required_instance_ci_template] = nil if params[:application_setting][:required_instance_ci_template].empty?
+    end
 
     remove_blank_params_for!(:elasticsearch_aws_secret_access_key, :eks_secret_access_key)
 
@@ -217,9 +220,7 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
     params.delete(:domain_denylist_raw) if params[:domain_denylist]
     params.delete(:domain_allowlist_raw) if params[:domain_allowlist]
 
-    params.require(:application_setting).permit(
-      visible_application_setting_attributes
-    )
+    params[:application_setting].permit(visible_application_setting_attributes)
   end
 
   def recheck_user_consent?

ee/spec/controllers/admin/application_settings_controller_spec.rb

@@ -194,6 +194,14 @@ RSpec.describe Admin::ApplicationSettingsController do
             expect(ApplicationSetting.current.required_instance_ci_template).to be_nil
           end
         end
+
+        context 'without key' do
+          it 'does not set required_instance_ci_template to nil' do
+            put :update, params: { application_setting: {} }
+
+            expect(ApplicationSetting.current.required_instance_ci_template).to be == 'Auto-DevOps'
+          end
+        end
       end
     end