bootanalyze: sort timing points with averaged value

- it was sorted with 1st value and was confusing.

bug: 33210752
Test: python packages/services/Car/tools/bootanalyze/bootanalyze.py -r -c packages/services/Car/tools/bootanalyze/config.yaml -n 10

Change-Id: Id06e4e6887184183762b712b08057fa38385f9af
1 file changed