reformat build suffix so that the latest is always correct

[liqunfu]

Description:

we want to format the build_suffix to avoid (the 12th run on 20210630 vs the first run on 20210701):

    # 2021063012 > 20210701
    # in above 2021063012 is treated as the latest which is incorrect.
    # we want to convert the format to:
    # 20210630012 < 20210701001
    # where the first 8 digits are date. the last 3 digits are run count.
    # as long as there are less than 1000 runs per day, we will not have the problem.

[suffiank]

Great! This is needed.