LU-17005 obdclass: only print seconds for job_stats

LU-17005 obdclass: only print seconds for job_stats

Only print the seconds field for the job_stats snapshot_time: field.
Otherwise the addition of the usec and "secs.usec" units field can
break the output parsing.

There is no way to print only the seconds in lprocfs_stats_header(),
since all of the other snapshot_time: fields previously printed the
microseconds field also, so use seq_printf() with the old format.

Test-Parameters: trivial
Fixes: 5efb892396e3 ("LU-11407 obdclass: add start time to stats files")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I1bda709e3bc4231d42f6a98e7487f0b11445f056
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52212
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Feng Lei <flei@whamcloud.com>
Reviewed-by: Nathaniel Clark <nclark@whamcloud.com>