create arch specific baseos for ironic

[ashwindasr]

Fix cross-architecture package installation for ironic image build

The ironic image build was failing when trying to install aarch64 packages (grub2-efi-aa64, shim-aa64) during
cross-architecture EFI image creation. The build script creates EFI boot images for both x86_64 and aarch64 architectures,
but only x86_64 repositories were available.

Changes:

• Added rhel-9-baseos-rpms-x86_64 and rhel-9-baseos-rpms-aarch64 repository definitions in group.yml
• Updated ironic.yml to use both architecture-specific repositories instead of the generic rhel-9-baseos-rpms

This enables dnf --forcearch=aarch64 to successfully find and install aarch64 packages from the appropriate repository
during the build process.

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