Extract Bigtable instance type from InstanceInfo instead of deriving from clusters

[nickmoorman]

This PR makes a simple tweak to the Read function used for Terraform's google_bigtable_instance to extract the instance type from the bigtable.InstanceInfo fetched from the Bigtable Admin API instead of deriving it from the cluster configuration.

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review. They will authorize it to run through our CI pipeline, which will generate downstream PRs.

Thanks for your contribution! A human will be with you soon.

@rambleraptor, please review this PR or find an appropriate assignee.

[rileykarson]

LGTM- there's one small thing, I'm going apply it myself if I have permissions to do so.

Edit: Darn, looks like I don't. Do you mind applying that change?

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, 15e8075.

Pull request statuses

No diff detected in terraform-google-conversion.
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#1288
depends: hashicorp/terraform-provider-google#4730

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, d30fe62.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.