chore(registry): update s3cmd base image

[emosbaugh]

What this PR does / why we need it:

kurlsh/s3cmd:20251112-208b4d5 (alpine 3.16.9)
=============================================
Total: 2 (HIGH: 2, CRITICAL: 0)

┌────────────┬────────────────┬──────────┬────────┬───────────────────┬───────────────┬────────────────────────────────────────────────────┐
│  Library   │ Vulnerability  │ Severity │ Status │ Installed Version │ Fixed Version │                       Title                        │
├────────────┼────────────────┼──────────┼────────┼───────────────────┼───────────────┼────────────────────────────────────────────────────┤
│ musl       │ CVE-2025-26519 │ HIGH     │ fixed  │ 1.2.3-r3          │ 1.2.3-r4      │ musl libc 0.9.13 through 1.2.5 before 1.2.6 has an │
│            │                │          │        │                   │               │ out-of-bounds write ......                         │
│            │                │          │        │                   │               │ https://avd.aquasec.com/nvd/cve-2025-26519         │
├────────────┤                │          │        │                   │               │                                                    │
│ musl-utils │                │          │        │                   │               │                                                    │
│            │                │          │        │                   │               │                                                    │
│            │                │          │        │                   │               │                                                    │
└────────────┴────────────────┴──────────┴────────┴───────────────────┴───────────────┴────────────────────────────────────────────────────┘

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Steps to reproduce

Does this PR introduce a user-facing change?

Does this PR require documentation?

[github-actions]

Testgrid Run(s) Executing @ https://testgrid.kurl.sh/run/pr-5917-b58d48d-registry-3.0.0-k8s-docker-2026-02-24T14:51:20Z

[github-actions]

Testgrid Run(s) Executing @ https://testgrid.kurl.sh/run/pr-5917-b58d48d-velero-1.16.2-k8s-docker-2026-02-24T14:54:51Z