gitlab-ci: Select CUDA version explicitly in NVHPC job

The job added by commit 16a5c36795 (gitlab-ci: add nightly job testing
NVHPC with Ninja on Linux, 2022-11-21) started failing after CI hosts
were updated from NVIDIA driver version 520 to version 525.  Somehow
this causes the NVHPC multi-cuda `nvcc` wrapper to select CUDA 10.2
instead of 11.7 as with older driver versions.

As a workaround, add the preferred version of `nvcc` to the PATH.

Issue: #24225