Merge #11445

11445: Only use preview plans for --yes in experimental mode r=Frassle a=Frassle

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# Description

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Fixes #11444

## Checklist

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- [ ] I have added tests that prove my fix is effective or that my feature works
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- [x] I have run `make changelog` and committed the `changelog/pending/<file>` documenting my change
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Co-authored-by: Fraser Waters <fraser@pulumi.com>

changelog/pending/20221123--cli--up-yes-should-not-use-update-plans.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+  scope: cli
+  description: `up --yes` should not use update plans.

pkg/backend/apply.go

@@ -122,6 +122,11 @@ func PreviewThenPrompt(ctx context.Context, kind apitype.UpdateKind, stack Stack
 	// If there are no changes, or we're auto-approving or just previewing, we can skip the confirmation prompt.
 	if op.Opts.AutoApprove || kind == apitype.PreviewUpdate {
 		close(eventsChannel)
+		// If we're running in experimental mode then return the plan generated, else discard it. The user may
+		// be explicitly setting a plan but that's handled higher up the call stack.
+		if !op.Opts.Engine.Experimental {
+			plan = nil
+		}
 		return plan, changes, nil
 	}