Remove auto-increment primary key when saving as copy

[br41nslug]

Description

When saving as copy the code was looking for the is_generated flag in schema which can be false for primary keys. I've updated this check to look for the has_auto_increment flag instead which should always be true for auto-increment IDs.

Fixes #15771
Fixes ENG-179

Type of Change

• Bugfix
• Improvement
• New Feature
• Refactor / codestyle updates
• Other, please describe:

Requirements Checklist

• New / updated tests are included
• All tests are passing locally
• Performed a self-review of the submitted code

If adding a new feature:

• Documentation was added/updated. PR:

[br41nslug]

I've manually tested this on postgres and mysql against auto-increment IDs, manually entered IDs and Generated UUIDs. Would love to have some unit tests for this too but have not been able to manage that so far.

#15033 is still occurring on mysql.

[azrikahar]

I've manually tested this on postgres and mysql against auto-increment IDs, manually entered IDs and Generated UUIDs.

Nice catch to cover uuid special flag as well! 👍

Would love to have some unit tests for this too but have not been able to manage that so far.

Added an attempt for it in a follow up commit. Do feel free to vet the tests as it feels like the structure can still be improved, but it should help catch these scenarios for now. 🤞