[CD] Disable USE_MPI in XPU CI/CD wheel build (pytorch#159135)

XPU wheel build need source MPI for distributed XCCL backend build, but it also enable USE_MPI by default.
Pull Request resolved: pytorch#159135
Approved by: https://github.com/malfet

Author: chuanqi129

.ci/manywheel/build_xpu.sh

@@ -25,6 +25,7 @@ source /opt/intel/oneapi/mpi/latest/env/vars.sh
 export USE_STATIC_MKL=1
 export USE_ONEMKL=1
 export USE_XCCL=1
+export USE_MPI=0
 
 WHEELHOUSE_DIR="wheelhousexpu"
 LIBTORCH_HOUSE_DIR="libtorch_housexpu"

.ci/pytorch/build.sh

@@ -173,6 +173,7 @@ if [[ "$BUILD_ENVIRONMENT" == *xpu* ]]; then
   source /opt/intel/oneapi/mpi/latest/env/vars.sh
   # Enable XCCL build
   export USE_XCCL=1
+  export USE_MPI=0
   # XPU kineto feature dependencies are not fully ready, disable kineto build as temp WA
   export USE_KINETO=0
   export TORCH_XPU_ARCH_LIST=pvc