HPCC-8288 - Cache allocators

Use caching allocator implementation added recently
(see HPCC-8278)

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #3883 from jakesmith/hpcc-8288

HPCC-8288 - Cache allocators

Reviewed-By: Gavin Halliday <gavin.halliday@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>