fix(images): update PBR-affected service images (zed)

[Mohammed Naser (mnaser)]

Focused PBR image updates for stable/zed, addressing #4357. Companion to #4363.

Verified image updates

• magnum sha256:4584644f4c61cf899d80eb2191e0aca59f6413643c2970945e47b70eeb7499ef: published amd64 metadata contains pbr 7.1.2+a8e.0.3 and service version 15.0.2+a8e.2.1.

Remaining work — draft

• Merge, publish, and verify chore(deps): update vexxhost images (stable/zed) docker-cinder#1124 before adding its service image.
• Merge, publish, and verify chore(deps): update vexxhost images (stable/zed) docker-ironic#1272 before adding its service image.
• Merge, publish, and verify chore(deps): update vexxhost images (stable/zed) docker-octavia#1112 before adding its service image.

Scope is limited to Cinder, Ironic, Magnum, and Octavia images with the PBR correction and the release note. Heat helper images are excluded.

Validation: git diff --check passed. Image metadata verification is not runtime or deployment validation. CI and runtime validation remain outstanding.

Focused branch PRs

• main: fix(images): update OpenStack images with PBR fixes #4363
• stable/zed: fix(images): update PBR-affected service images (zed) #4364
• stable/2023.1: fix(images): update PBR-affected service images (2023.1) #4365
• stable/2023.2: fix(images): update PBR-affected service images (2023.2) #4366
• stable/2024.1: fix(images): update PBR-affected service images (2024.1) #4367
• stable/2024.2: fix(images): update PBR-affected service images (2024.2) #4368
• stable/2025.1: fix(images): update PBR-affected service images (2025.1) #4369
• stable/2025.2: fix(images): update PBR-affected service images (2025.2) #4370