Fix CUDA build failure on AutoDL cloud platforms

[pockers21]

Problem

As reported in issue #13893, the current CUDA build configuration in ci/run.sh fails on AutoDL cloud machines:

if [ ! -z ${GG_BUILD_CUDA} ]; then
    CMAKE_EXTRA="${CMAKE_EXTRA} -DGGML_CUDA=ON -DCMAKE_CUDA_ARCHITECTURES=native"
fi

Root Cause

The issue appears to be that CMAKE_CUDA_ARCHITECTURES=native fails on cloud platforms,
likely due to restricted GPU introspection capabilities.

Reproduction

This can be reproduced with a minimal test script:

#!/bin/bash

mkdir cmake_arch_test && cd cmake_arch_test

cat << 'EOF' > CMakeLists.txt
cmake_minimum_required(VERSION 3.18)
project(test_cuda_arch LANGUAGES CUDA)

message(STATUS "CMAKE_CUDA_ARCHITECTURES: ${CMAKE_CUDA_ARCHITECTURES}")
message(STATUS "CMAKE_CUDA_COMPILER_TOOLKIT_ROOT: ${CMAKE_CUDA_COMPILER_TOOLKIT_ROOT}")

add_executable(test_cuda test.cu)
EOF

cat << 'EOF' > test.cu
int main() { return 0; }
EOF

rm -rf build && mkdir build && cd build
cmake -DCMAKE_CUDA_ARCHITECTURES=native .. 2>&1 | grep -E "(CMAKE_CUDA_ARCHITECTURES|architecture|fatal|error)"

This script produces the nvcc fatal : Unsupported gpu architecture 'compute_' error on AutoDL machines, but works fine on physical machines.

[pockers21]

@ggerganov Hi! This PR has been waiting for review for a while. Could you please take a look when you have time?