Remove old Software Helpdesk post stub

There were two posts on launch of the HIFIS Software helpdesk in mid 2020; but only one should remain; the other should be deleted.

Redirect is implemented to link from the latter to the former, just in case somebody has archived the wrong link.

assigned to @jandt-desy

changed the description

requested review from @frust45

approved this merge request

Thanks for spotting!

merged

mentioned in commit f9a33b18