fix(ec2): update EBS io2 and gp3 max volume size to 64 TiB

[syukawa-gh]

Closes #37045
AWS increased the maximum volume size for gp3 and io2 to 64 TiB (65536 GiB). CDK validation was incorrectly limiting these to 16 TiB.
Exemption Request: Validation constant change, no integration test needed.

[aws-cdk-automation]

The pull request linter fails with the following errors:

❌ Fixes must contain a change to an integration test file and the resulting snapshot.

If you believe this pull request should receive an exemption, please comment and provide a justification. A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed, add Clarification Request to a comment.

✅ A exemption request has been requested. Please wait for a maintainer's review.

[syukawa-gh]

Exemption Request: This fix updates EBS volume size validation constants to match current AWS limits (64 TiB for io2 and gp3). Unit tests are included. Integration test is not applicable as this is a synth-time validation change.

[syukawa-gh]

Correction to my previous comment: After reviewing the diff more carefully, this PR needs unit tests to be added. I will update this PR with the required tests. The Exemption Request above should be disregarded for the unit test requirement.

[syukawa-gh]

To clarify my earlier comments: unit tests are already included in this PR. The "Correction" comment above was posted in error. The exemption request is for the integration test only — this updates synth-time validation constants to match current AWS limits, and the unit tests verify the updated validation.