Replace PRODUCT_DISABLE_SCUDO with MALLOC_LOW_MEMORY.

The PRODUCT_DISABLE_SCUDO only removes scudo from the list of
sanitizers. It doesn't change the allocator to be used.

Instead use MALLOC_LOW_MEMORY := true, which causes a device
to use a low memory version of the allocator.

Bug: 318756974

Test: Treehugger.
Change-Id: Idaf57cfa4fa723ce8d7f285b2bad8ec29059f0df