The memory-optimized X4 machine series offers additional bare metal machine

## Feature Feature The memory-optimized X4 machine series offers additional bare metal machine types with 6 TB, 8 TB, and 12 TB of memory. For more information, see [X4 machine series](https://cloud.google.com/compute/docs/memory-optimized-machines#x4%5Fseries). ## Issue Issue Workloads on A4 VMs might experience interruptions due to a firmware issue for NVIDIA B200 GPUs. To help prevent the issue, we recommend resetting the GPUs on A4 VMs at least once every 60 days. For more information, see the[known issue](https://cloud.google.com/ai-hypercomputer/docs/troubleshooting/known-issues#a4-firmware).