feat(aws_docdb_cluster): upgrade the default engine_version to 5.0.0

[gmeligio]

what

Upgrade the default engine_version to the latest as of today, which is 5.0.0.

why

• To get the new features available and also the compatibility with MongoDB 5.0 API.
• To avoid the problems that come with edge cases when upgrading from 3.6/4.0 to 5.0, if we wanted 5.0 since the beginning but forgot to specify it.

references

• https://docs.aws.amazon.com/documentdb/latest/developerguide/compatibility.html#compatibility-whatsnew-5
• https://docs.aws.amazon.com/documentdb/latest/developerguide/docdb-mvu.html#mvu-prerequisites

[RoseSecurity]

/terratest

[RoseSecurity]

Thank you for identifying this improvement and contributing! A few additions may be required for this change:

• Updating the cluster_family to maintain parity with the version increase
• Amazon DocumentDB 4.0/5.0 does not support r4.* instance_classes so that parameter will need to be updated to r5 as well

[Nuru]

I am opposed to updating the default, as that is a potentially breaking change, and as long as the default value is still supported, I think the disruption is not worth the benefit.

[gmeligio]

Thank you for identifying this improvement and contributing! A few additions may be required for this change:

• Updating the cluster_family to maintain parity with the version increase
• Amazon DocumentDB 4.0/5.0 does not support r4.* instance_classes so that parameter will need to be updated to r5 as well

In that case, db.t4g.medium would be a cost-effective default supported in DocumentDB 4.0/5.0.

I am opposed to updating the default, as that is a potentially breaking change, and as long as the default value is still supported, I think the disruption is not worth the benefit.

OK. The idea was a nice to have, but it's not essential. Seeing that it's a breaking change, I'll close the PR.