Fix the stats log in lmkd

1. let logs be written to statsd directly like all other stats logs.
   + stats log should not write to logd anymore(b/78239479)
2. fixed the log format
   + need to embed the elapsed real time in the log
3. fixed the log context reuse problem
   +reset the log context buffer and internal state before reuse

Bug: 78603347
Bug: 78239479

Test: tested with alloc_stress, and saw logs written to statsd

performance measurement (memory & cpu):
https://paste.googleplex.com/5508158646648832

Change-Id: I345f0eace8ba1687ff480fb88e9abba1d8533f76