resource/aws_db_proxy_default_target_group: Make connection_pool_config Optional

[gdavison]

The documentation for aws_db_proxy_default_target_group states that connection_pool_config is optional and the API does not require it.

Closes #16285

Release note for CHANGELOG:

* resource/aws_db_proxy_default_target_group: Make `connection_pool_config` optional

Output from acceptance testing:

$ make testacc TESTARGS='-run=TestAccAWSDBProxyDefaultTargetGroup_'

--- PASS: TestAccAWSDBProxyDefaultTargetGroup_disappears (663.38s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_EmptyConnectionPoolConfig (674.40s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_MaxConnectionsPercent (697.92s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_ConnectionBorrowTimeout (776.49s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_SessionPinningFilters (793.09s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_MaxIdleConnectionsPercent (795.58s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_Basic (795.63s)
--- PASS: TestAccAWSDBProxyDefaultTargetGroup_InitQuery (835.42s)

[anGie44]

LGTM 🚀

output of added acceptance test:

--- PASS: TestAccAWSDBProxyDefaultTargetGroup_EmptyConnectionPoolConfig (689.41s)

[anGie44]

cool! never thought to use this method for Lists as well

[ghost]

This has been released in version 3.18.0 of the Terraform AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template for triage. Thanks!

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!