[Table Logging] Save the last evicted value per column.

Fixes: 272016422

Test: atest TableLogBufferTest TableChangeTest

Test: systraces to verify the saving doesn't vastly increase log time.
Verify that `wifiEnabled` still shows up in the table log.

Test: Keep changing wifi networks (but leave wifi enabled always).
See bug for more information, but tl;dr: Average log takes 35us.

Change-Id: I48a0acc7b1191e3b3262e0401991afe76099b1a4