Drop recommendation to use -provider= on import

[sethvargo]

This was deprecated in 0.12 and is removed in 0.13.

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

Drop recommendation to use -provider= on import in documentation

[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.

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

@megan07, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 151 files changed, 453 deletions(-))
Terraform Beta: Diff ( 182 files changed, 86 insertions(+), 632 deletions(-))

[modular-magician]

I have triggered VCR tests based on this PR's diffs. See the results here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=141465"

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccActiveDirectoryDomainTrust_activeDirectoryDomainTrustBasicExample|TestAccBigqueryDataTransferConfig|TestAccComputeInstanceFromTemplate_basic|TestAccContainerNodePool_withInvalidKubeletCpuManagerPolicy|TestAccPubsubSubscription_pubsubSubscriptionPullExample You can view the result here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=141471"

[megan07]

Thank you! We probably want to look through other, non-generated, documentation and make these changes as well. I can open a new issue for that, if you don't want to include it here.

[sethvargo]

@megan07 done

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 177 files changed, 3 insertions(+), 528 deletions(-))
Terraform Beta: Diff ( 211 files changed, 95 insertions(+), 722 deletions(-))

[modular-magician]

I have triggered VCR tests based on this PR's diffs. See the results here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=142272"

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccActiveDirectoryDomainTrust_activeDirectoryDomainTrustBasicExample|TestAccContainerNodePool_withInvalidKubeletCpuManagerPolicy You can view the result here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=142274"

[megan07]

@sethvargo thank you!