[modeling utils] revamp `from_pretrained(..., low_cpu_mem_usage=True)` + tests (#16657)
* add low_cpu_mem_usage tests
* wip: revamping
* wip
* install /usr/bin/time
* wip
* cleanup
* cleanup
* cleanup
* cleanup
* cleanup
* fix assert
* put the wrapper back
* cleanup; switch to bert-base-cased
* Trigger CI
* Trigger CI