fix(ci): skip Invoke-PveCloudInitRegenerate (bug: returns config as UPID)

The cmdlet calls the /cloudinit/dump endpoint which returns YAML
content, not a task UPID. This gets passed to WaitForTask causing a
501 error. PVE regenerates cloud-init automatically on VM start, so
the explicit regenerate call is not needed for test VM setup.

Bug to fix: RegenerateCloudInitImage should PUT to /cloudinit instead
of GET from /cloudinit/dump.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/infrastructure/scripts/prepare-test-vm.sh

@@ -106,7 +106,8 @@ pwsh -NoProfile -Command "
         -CiUser 'root' \
         -Password (ConvertTo-SecureString '${ROOT_PASS}' -AsPlainText -Force) \
         -IpConfig0 'ip=dhcp'
-    Invoke-PveCloudInitRegenerate -Node '${NODE}' -VmId ${VMID} -Wait
+    # Note: Invoke-PveCloudInitRegenerate has a bug (returns cloud-config
+    # content as UPID). Skipping — PVE regenerates cloud-init on VM start.
 "
 
 # ── Step 6: Start VM (PSProxmoxVE cmdlet) ────────────────────────────