Remove projects being moved into from system/core into system/memory

The following directories are being moved into separate projects under
system/memory:
  platform/system/memory/libion
  platform/system/memory/libmeminfo
  platform/system/memory/libmemtrack
  platform/system/memory/libmemunreachable
  platform/system/memory/lmkd

Remove them from system/core.

Bug: 141634854
Test: build and boot
Change-Id: I0ecc0668a281ec360133c8472bbf12ece92116d2
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Merged-In: Ica64900cd8af273fdffd321591acf3a566f04355
Merged-In: I98793edd10954058448727635f101219f71d3ccf