Backport of check for cancellation before apply confirmation into v1.2

[ghost]

Backport

This PR is auto-generated from #30979 to be assessed for backporting due to the inclusion of the label 1.2-backport.

The below text is copied from the body of the original PR.

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When executing an apply with no plan, it's possible for a cancellation
to arrive during the final batch of provider operations, resulting in no
errors in the plan. The run context was next checked during the
confirmation for apply, but in the case of -auto-approve that
confirmation is skipped, resulting in the canceled plan being applied.

Make sure we directly check for cancellation before confirming the plan.

Fixes #30918

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[github-actions]

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