lxd/operations: Return failed operation state from wait endpoint

[IzzaldinSamir]

• I have read the contributing guidelines and attest that all commits in this PR are signed off, cryptographically signed, and follow this project's commit structure.
• I have checked and added or updated relevant documentation.

Root Cause

The wait endpoint commits to an HTTP 200 OK before blocking on the operation. When op.Wait returned an operation error, the handler attempted to render a second HTTP error response instead of returning the operation state. As a result, clients (like lxc network) interpreted failed asynchronous operations as successful because they received a 200 OK without the failure payload.

The Fix

Instead of checking the error from op.Wait(ctx), we now call op.Render() after the wait returns to fetch the actual final state of the operation (which includes failures and timeouts) and return it to the client via a SyncResponse.

Added regression coverage in test/suites/operations.sh to ensure duplicate network creations properly return the failure state.

Fixes #18715

[0xSA7]

Hey @IzzaldinSamir!

If you closed this because of the failed DCO or CLA checks, no need to restart from scratch! That happens all the time with first contributions.
Just noticed a couple of CI checks was blocking the PR:

• DCO Check Failed: Mismatch between git author name and Signed-off-by header

• Canonical CLA: Requires a signed CLA.

[IzzaldinSamir]

Hey @IzzaldinSamir!

If you closed this because of the failed DCO or CLA checks, no need to restart from scratch! That happens all the time with first contributions. Just noticed a couple of CI checks was blocking the PR:

• DCO Check Failed: Mismatch between git author name and Signed-off-by header
• Canonical CLA: Requires a signed CLA.

Hey @0xSA7, thanks for looking out! I actually caught a minor code duplication in my Go logic right after opening this, and since my browser editor was acting up with the Git Amend command for the DCO signature, I just spun up a clean branch and recreated it over at #18830. Everything is green and good to go now. I really appreciate the help though!