Remove integrations from project import / export

We have trouble importing / exporting projects with Services / Integrations. As per discussion below we do want to remove the export / import of Services / Integrations as it would allow to export confidential information (e.g. passwords / tokens): #220342 (comment 357470473)

Original Description of: Fix export/import projects with issue tracker services

When we export/import a project with a service using an external data fields table the import functionality is not importing the service data.

Steps to reproduce

1. Create a project
2. Configure any of those services:
   • Jira
   • Redmine
   • YouTrack
   • Bugzilla
   • CustomIssueTracker
3. Export the project
4. Import the project -> The service configuration is gone