[sanitizer] Consolidate some LowLevelAllocators to one

This removes and replaces usage of a few LowLevelAllocators with a single one
provided by sanitizer_common. Functionally, there should be no difference
between using different allocators vs the same one. This works really well
with D158783 which controls the size of each allocator mmap to significantly
reduce fragmentation.

This doesn't remove them all, mainly the ones used by asan and the flag parser.

Differential Revision: https://reviews.llvm.org/D158786