lmkd: Enable new kill strategy, add and adjust required system properties

Enable new kill strategy when PSI mode is used in combination with
ro.lmk.use_minfree_levels=false. Adjust ro.lmk.swap_free_low_percentage,
introduce ro.lmk.psi_partial_stall_ms and ro.lmk.psi_complete_stall_ms
system properties to support two levels of PSI events measuring partial
and complete stalls. Add ro.lmk.use_new_strategy system property to switch
to the old strategy if necessary.

Bug: 132642304
Test: lmkd_unit_test, ACT memory pressure tests
Change-Id: I6f1b65e19dbe9b58c862e5e4255270c82f0afb9a
Signed-off-by: Suren Baghdasaryan <surenb@google.com>