ANDROID: MGLRU: Don't skip anon reclaim if swap low

MGLRU tries to avoid doing unnecessary anon reclaim work if swap is
low by checking if the available swap is less than the MIN_BATCH_SIZE
(256kB). This can lead to unintened consequences where PSI pressure is
less and LMKD doesn't wake up in time to avoid file cache thrashing.

Remove this check to preserve the old bahavior. This can be improved
later on once we have a low swap notification event from the kernel.

Bug: 268574308
Change-Id: Id381316931a9cf6e7ea8b1ea7800c77f176c9892
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>