UCS/MPOOL: Fix valgrind error.
UCS/MPOOL: Fix valgrind error.

shssf/ucx,sergsagal1/ucx_rocm,shssf/ucx,manjugv/ucx,manjugv/ucx,sergsagal1/ucx_rocm,manjugv/ucx,shssf/ucx,abouteiller/ucx,sergsagal1/ucx_rocm,abouteiller/ucx,abouteiller/ucx,abouteiller/ucx