Update libaom-av1 default options

[vibhoothi]

Hi,

Setting to 1000 for Keyframe minimum and maximum, might give us crash in encoding as libaom is having bug on two-pass on certain clips

rd_tool/metrics_gather.sh

Line 210 in fb2141d

$($TIMER $AOMENC --codec=$CODEC --ivf --frame-parallel=0 --tile-columns=0 --auto-alt-ref=2 --cpu-used=0 --passes=2 --threads=1 --kf-min-dist=$KFINT --kf-max-dist=$KFINT --lag-in-frames=25 --end-usage=q --cq-level=$x --test-decode=fatal -o $BASENAME.ivf $EXTRA_OPTIONS $FILE > "$BASENAME-stdout.txt")

CF: https://bugs.chromium.org/p/aomedia/issues/detail?id=2984

Secondly, setting auto-alt-ref >1 is deprecated since 2018, we could also remove that and keep to 1
https://aomedia-review.googlesource.com/c/aom/+/68381