Switch usage to vendored Open MPI in TheRock RCCL CI

[marbre]

therock-rccl-ci-linux.yml still depends on a customized manylinux image with Open MPI installed:

rocm-systems/.github/workflows/therock-rccl-ci-linux.yml

Line 23 in e7d568f

image: ghcr.io/rocm/therock_build_manylinux_x86_64@sha256:1f1ce0ab151146c7f86ee4345be74c42d8ca83200d9d26843e8a71df01ecad4e

Open MPI is now available bundled (ROCm/TheRock@82348d8) and PR ROCm/TheRock#3897 fixes and rocprofiler issue. However, the custom paths in the manylinux image (https://github.com/ROCm/TheRock/blob/0b0813f3eaed62af3362985596b217deae9123e2/dockerfiles/build_manylinux_rccl_x86_64.Dockerfile#L126-L129) override other settings and as a result the binaries will pick up Open MPI library from /opt/openmpi-5.0.8/ instead of the bundled one.

The custom image should be dropped in favor of the standard image with no Open MPI preinstalled. In addition the MPI tools shipped as part of TheRock must be used instead of any system installed ones.