Change default recode rule for good speed 0 and best.

Change default recode rule for good speed 0 and best.

Changes the default recode rule for Speed 0 and best quality
from ALLOW_RECODE to ALLOW_RECODE_KFARFGF.

Tested on the NF, hdres, midres and lowres test sets, this setting
when combined with patch I40cb559... now performs "as well" in
metrics terms (in fact it came out a tiny amount better overall)
but encode time is 9.6%  faster (measured as the average
from 27 mid rate local encodes on clips in the derf/lowres set.

Change-Id: I8c781c0cdfa3a9929cd9406d15582fce47d6ae3b