feat: added confidential-nodes flag for node-pools

[t-indumathy]

Motivation
The current set of confidential node support is available only at the cluster level, but the confidential node support at the node level is required to have new node pools created with confidential nodes.

Summary of changes
Added enable_confidential_nodes variable at the node pool level.

P.S: This is addressing the issue #1386 and has same changes as that of the PR #1756. As the PR author has not responded for the review comments, I'm thus creating a fresh PR as this feature is needed at the earliest.

Fixes: #1386
Closes: #1756

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[apeabody]

/gcbrun

[apeabody]

Thanks for the contribution @t-indumathy!

Can you please document the new variable here:
https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/blob/master/autogen/main/README.md?plain=1#L190

[t-indumathy]

Thanks for the contribution @t-indumathy!

Can you please document the new variable here: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/blob/master/autogen/main/README.md?plain=1#L190

This is already present at https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/blob/master/autogen/main/README.md?plain=1#L204 .

[apeabody]

/gcbrun

[apeabody]

/gcbrun

[t-indumathy]

@apeabody Can you pls let me know the details on why the pipeline is unsuccessful.

[apeabody]

@apeabody Can you pls let me know the details on why the pipeline is unsuccessful.

Hi @t-indumathy - I'm going to re-run the tests. A node pool failed to create, but I don't believe it's related to this change.

[apeabody]

/gcbrun

[t-indumathy]

@apeabody can you pls backport this feature to v30.0.

[apeabody]

@apeabody can you pls backport this feature to v30.0.

Hi @t-indumathy - Unfortunately we don't do backport releases and instead recommend updating to the latest module version, however if required you could fork the v30.0 release for your changes and use a custom module source. Best Wishes!