Check if `licenses` table exists before loading the current license.

What does this MR do?

Check if licenses table exists before loading the current license.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

The upgrade from CE to EE is broken due to an issue with the licenses table not existing and the initializer expecting it to be there.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #3280 (closed)