Skip graph cycle validation when using the graph command

[dsa0x]

The graph command should be able to generate graphs with cycles. However, this is only accepted when the -draw-cycles option is given. In this case, the graph validation would be skipped.

Fixes #34639

Target Release

1.11.x

Draft CHANGELOG entry

BUG FIXES

• terraform graph -draw-cycles: Fix terraform graph command, and indicate the cycles.

[github-actions]

The equivalence tests will be updated. Please verify the changes here.

[jbardin]

This isn't the only Validate call, it needs to be called earlier too (this actually should never fail right now). You can't run TransitiveReduction if there are cycles, so we call Validate at least once when building the graph.

[dsa0x]

There are 3 Validate calls. This one, the one in TransitiveReductionTransfomer, and one that is called on a subgraph during the graph walk.

This validation skip is only about building the graph, which is already done before a walk, so I think the latter matters less here. (maybe it would help for it to be called SkipGraphBuildValidation
Luckily, the one in the transitive reduction transformer does not return an error, it is simply a gate to prevent running TransitiveReduction on a cyclic graph.

However, I could try a different approach which would put the skipping step in the Validate method itself, so that every point where it is called gets that behaviour

[dsa0x]

What do you think of this other approach? @jbardin
In 4675020, I moved the skip step to the Validate method, therefore it would not return an error if we are asked to skip validation. However, because the TransitiveReduction should not run if there are validation errors, we have to do an additional early return in the transformer.

[jbardin]

Oh, I forgot that the transformer call drops the error! In that case yes, it is probably easiest to just return early here. Any errors that arise with the subgraphs are entirelyTerraform's problem, so not something a user would want to try debug with the graph.

[github-actions]

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