aws_ec2_instance: allow adjusting ipv6_address_count without replacing the instance

[hfinucane]

Description

This will allow adjusting the ipv6_address_count address on an instance's primary NIC without replacing the instance.

Relations

Closes #33707

Output from Acceptance Testing

% make testacc TESTS=TestAccEC2Instance_IPv6AddressCount PKG=ec2
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 20 -run='TestAccEC2Instance_IPv6AddressCount'  -timeout 360m
=== RUN   TestAccEC2Instance_IPv6AddressCount
=== PAUSE TestAccEC2Instance_IPv6AddressCount
=== CONT  TestAccEC2Instance_IPv6AddressCount
--- PASS: TestAccEC2Instance_IPv6AddressCount (140.24s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/ec2	144.286s

[github-actions]

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[github-actions]

Welcome @hfinucane 👋

It looks like this is your first Pull Request submission to the Terraform AWS Provider! If you haven’t already done so please make sure you have checked out our CONTRIBUTOR guide and FAQ to make sure your contribution is adhering to best practice and has all the necessary elements in place for a successful approval.

Also take a look at our FAQ which details how we prioritize Pull Requests for inclusion.

Thanks again, and welcome to the community! 😃

[ewbankkit]

LGTM 🚀.

% make testacc TESTARGS='-run=TestAccEC2Instance_IPv6\|TestAccEC2Instance_basic\|TestAccEC2Instance_ipv6AddressCountAndSingleAddressCausesError' PKG=ec2 ACCTEST_PARALLELISM=3
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 3  -run=TestAccEC2Instance_IPv6\|TestAccEC2Instance_basic\|TestAccEC2Instance_ipv6AddressCountAndSingleAddressCausesError -timeout 360m
=== RUN   TestAccEC2Instance_basic
=== PAUSE TestAccEC2Instance_basic
=== RUN   TestAccEC2Instance_IPv6_supportAddressCount
=== PAUSE TestAccEC2Instance_IPv6_supportAddressCount
=== RUN   TestAccEC2Instance_ipv6AddressCountAndSingleAddressCausesError
=== PAUSE TestAccEC2Instance_ipv6AddressCountAndSingleAddressCausesError
=== RUN   TestAccEC2Instance_IPv6_supportAddressCountWithIPv4
=== PAUSE TestAccEC2Instance_IPv6_supportAddressCountWithIPv4
=== RUN   TestAccEC2Instance_IPv6AddressCount
=== PAUSE TestAccEC2Instance_IPv6AddressCount
=== RUN   TestAccEC2Instance_basicWithSpot
=== PAUSE TestAccEC2Instance_basicWithSpot
=== CONT  TestAccEC2Instance_basic
=== CONT  TestAccEC2Instance_basicWithSpot
=== CONT  TestAccEC2Instance_IPv6_supportAddressCountWithIPv4
--- PASS: TestAccEC2Instance_basic (121.12s)
=== CONT  TestAccEC2Instance_ipv6AddressCountAndSingleAddressCausesError
--- PASS: TestAccEC2Instance_ipv6AddressCountAndSingleAddressCausesError (5.32s)
=== CONT  TestAccEC2Instance_IPv6_supportAddressCount
--- PASS: TestAccEC2Instance_basicWithSpot (156.62s)
=== CONT  TestAccEC2Instance_IPv6AddressCount
--- PASS: TestAccEC2Instance_IPv6_supportAddressCountWithIPv4 (182.15s)
--- PASS: TestAccEC2Instance_IPv6_supportAddressCount (170.51s)
--- PASS: TestAccEC2Instance_IPv6AddressCount (178.74s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/ec2	355.332s

[ewbankkit]

@hfinucane Thanks for the contribution 🎉 👏.

[github-actions]

This functionality has been released in v5.41.0 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. Thank you!

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.