Remove old data compatibility troubleshooting section

What does this Merge Request do?

Remove an old section of the troubleshooting docs that say that GDK is not compatible with PostgreSQL 10.

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.