fix: filter ARM64 images from boot disk selection

[aditsharma55]

Summary:

• Filters out ARM64 images from boot disk selection to prevent BootDisk CPU architecture "arm64" should match platform "amd64" errors on Nebius instance creation
• Nebius recently added ARM64 images to their public catalog; when getWorkingPublicImageID lists all images, an ARM64 image could be selected before an AMD64 one depending on API listing order
• Adds ubuntu24.04-cuda13.0 and ubuntu24.04-cuda12 to knownFamilies.
• Updates commonFamilies with new Ubuntu 24.04 image families (ubuntu24.04-cuda13.0, ubuntu24.04-cuda12, ubuntu24.04-driverless).

Changes
instance.go — buildDiskCreateRequest(), getWorkingPublicImageID(), resolveImageFamily()

• Added ubuntu24.04-cuda13.0, ubuntu24.04-cuda12 to knownFamilies list.
• Added ARM64 architecture check after GetLatestByFamily call — if an unknown family resolves to an ARM64 image (compute.ImageSpec_ARM64), falls through to the filtered getWorkingPublicImageID instead of using it directly.
• Added ARM64 filter in getWorkingPublicImageID loop — skips images where image.Spec.GetCpuArchitecture() == compute.ImageSpec_ARM64, ensuring only AMD64-compatible images are selected for boot disks.
• Added ubuntu24.04-cuda13.0, ubuntu24.04-cuda12, ubuntu24.04-driverless to commonFamilies list.