resource/aws_redshift_cluster: Update default value of encrypted to true to match AWS default

[gdavison]

Rollback Plan

If a change needs to be reverted, we will publish an updated version of the provider.

Changes to Security Controls

None

Description

AWS defaults to encryption at rest, but the default value of encrypted is false. This PR updates the default value to true. It also fixes a bug where encryption cannot be set to false on creation.

Additionally removes unneeded availability zone restrictions on acceptance tests.

Relations

Closes #42598

References

Output from Acceptance Testing

% make testacc TESTS=TestAccXXX PKG=ec2

...

[github-actions]

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[github-actions]

✅ Thank you for correcting the previously detected issues! The maintainers appreciate your efforts to make the review process as smooth as possible.