iso: pin NVIDIA driver/DCGM to DGX OS 7.5.0-validated combo

590.48.01/DCGM 4.6.0-1 was never a deliberate compatibility choice — the
driver version traces back to a CDN 404 on the originally pinned
550.54.15 (commit 559fc29), and DCGM was bumped twice since purely
because NVIDIA pulled the previously-pinned core package from the repo
(6dee8f3, b2e177a). The 590 branch only has two point releases so far,
and its nvvs plugin fails dcgmi diag with "Detected driver major
version 0 is not between the required versions 346 and 2000" on H100 —
confirmed via a staging support bundle.

Switch to 580.126.20 / DCGM 4.5.2-1, the combo NVIDIA's own DGX OS 7.5.0
release notes validate for H100. Both packages confirmed present in the
NVIDIA CUDA debian12/x86_64 apt repo.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

iso/builder/VERSIONS

@@ -1,7 +1,7 @@
 DEBIAN_VERSION=12
 DEBIAN_KERNEL_ABI=auto
-NVIDIA_DRIVER_VERSION=590.48.01
-NVIDIA_FABRICMANAGER_VERSION=590.48.01-1
+NVIDIA_DRIVER_VERSION=580.126.20
+NVIDIA_FABRICMANAGER_VERSION=580.126.20-1
 NCCL_VERSION=2.28.9-1
 NCCL_CUDA_VERSION=13.0
 NCCL_SHA256=2e6faafd2c19cffc7738d9283976a3200ea9db9895907f337f0c7e5a25563186
@@ -9,7 +9,7 @@ NCCL_TESTS_VERSION=2.13.10
 NVCC_VERSION=12.8
 CUBLAS_VERSION=13.1.1.3-1
 CUDA_USERSPACE_VERSION=13.0.96-1
-DCGM_VERSION=4.6.0-1
+DCGM_VERSION=4.5.2-1
 JOHN_JUMBO_COMMIT=67fcf9fe5a
 ROCM_VERSION=6.3.4
 ROCM_SMI_VERSION=7.4.0.60304-76~22.04