Increase IAM custom role length validation to match API.

[danawillow]

Upstreams hashicorp/terraform-provider-google#3660

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[all]

[terraform]

[terraform-beta]

[ansible]

[inspec]

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[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
This PR seems not to have generated downstream PRs before, as of cb0c577.

Pull request statuses

No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I built this PR into one or more new PRs on other repositories, and when those are closed, this PR will also be merged and closed.
depends: hashicorp/terraform-provider-google-beta#728
depends: GoogleCloudPlatform/terraform-google-conversion#82
depends: hashicorp/terraform-provider-google#3664