Optimize QEMU flags for amd64 on arm64
As a follow-up to !102, we should look into optimizing QEMU flags for amd64 on arm64. CI currently takes ~700 seconds to run //qemu:test-amd64.
As a follow-up to !102, we should look into optimizing QEMU flags for amd64 on arm64. CI currently takes ~700 seconds to run //qemu:test-amd64.