Remove javascripts/pages/admin/services directory

Service templates were deprecated in GitLab 14.0.
This directory is a left-over artefact of this deprecation.
It is not used.

In this commit, we remove this directory.

app/assets/javascripts/pages/admin/services/edit/index.js

-import IntegrationSettingsForm from '~/integrations/integration_settings_form';
-
-const integrationSettingsForm = new IntegrationSettingsForm('.js-integration-settings-form');
-integrationSettingsForm.init();

app/assets/javascripts/pages/admin/services/index/index.js

-import PersistentUserCallout from '~/persistent_user_callout';
-
-const callout = document.querySelector('.js-service-templates-deprecated');
-PersistentUserCallout.factory(callout);