Update cron timezone label in pipeline schedules and associated translations
This grows out of conversations here: https://gitlab.com/gitlab-org/gitlab-ce/issues/32565#note_30316385
"Cron Timezone" label could be misleading could be renamed to "Schedule Timezone" or, in my opinion, just "Timezone". This parameter affects also the "predefined" cron definitions, but it could be not so simple to understand otherwise.
@dimitrieh agreed that it should be just "Timezone"
This is being addressed separately from the issue where it was raised, because the work for that issue was basically done when the idea was suggested, and because it would also involve translations of the label, which seemed a bit out of scope.
Edited by Jason Yavorska