axolotl: lmkd: kill heaviest task instead of any eligible task

Also remove min oom_adj score override for critical tasks as well
as log_stats, which is true by default already.

Change-Id: I1ac259ccd21b4e9c56822bf55f243877979852e1
Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>