fix(hypervisors): prevent double --initramfs flag in Cloud Hypervisor command

[mdryaan]

Description

BuildExecCmd in cloud_hypervisor.go appended --initramfs unconditionally for both args.InitrdPath and extraMonArgs.ExtraInitrd. When both were set, the Cloud Hypervisor command line contained two --initramfs flags and Cloud Hypervisor rejected it. Apply the same priority-fallback logic already used by the Firecracker implementation: resolve to args.InitrdPath if set, otherwise fall back to extraMonArgs.ExtraInitrd, and append at most one --initramfs.

Related issues

• Fixes Cloud Hypervisor BuildExecCmd should not add two --initramfs flags #679

How was this tested?

Added TestCloudHypervisorSingleInitrd to pkg/unikontainers/hypervisors/cloud_hypervisor_test.go. The test calls BuildExecCmd with both args.InitrdPath and a mock unikernel returning a non-empty ExtraInitrd, then counts --initramfs occurrences in the result.

Before fix:

After fix:

Run with:
go test ./pkg/unikontainers/hypervisors/ -v -run TestCloudHypervisorSingleInitrd

golangci-lint run passes with 0 issues. make builds successfully.

LLM usage

N/A

Checklist

• I have read the contribution guide.
• The linter passes locally (make lint).
• The e2e tests of at least one tool pass locally (make test_ctr, make test_nerdctl, make test_docker, make test_crictl).
• If LLMs were used: I have read the llm policy.

[netlify]

✅ Deploy Preview for urunc canceled.

Name	Link
🔨 Latest commit	777e38e
🔍 Latest deploy log	https://app.netlify.com/projects/urunc/deploys/6a05485391838d0008856ba3

[mdryaan]

Hey @cmainas , Could you please have a look at this PR whenever you have time? Thanks!