cmsImportUser overwrites .itime_contest

[prandla]

we have a script that basically runs cmsImportUser to grab all new users from contest.yaml, and then runs cmsImportContest to update the contest/tasks. however, because of the way .itime_contest is used, cmsImportUser actually also touches .itime_contest, despite not importing the contest parameters. this means that the cmsImportContest actually never updates the contest parameters.

i guess we should move the itime_contest writing operation to a different place?