curation labels cannot be updated when creationTime is null and the label was set before DV 6.7

[ffritze]

What steps does it take to reproduce the issue?
If a dataset has curation labels which were set before DV release 6.7, the labels cannot be updated neither API call or GUI.

• When does this issue occur?
  If you want to update the curation label via API call or GUI.

• Which page(s) does it occurs on?
  On every page the curation label is displayed

• What happens?

• To whom does it occur (all users, curators, superusers)?
  All users

• What did you expect to happen?
  The curation label should change.

Which version of Dataverse are you using?
v6.7

Any related open or closed issues to this bug report?

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Are you thinking about creating a pull request for this issue?
Help is always welcome, is this bug something you or your organization plan to fix?

[ffritze]

I have developd a fix for this issue: TIK-NFL@abad78c

[pdurbin]

@ffritze thanks for the issue and the commit! Do you want to go ahead and make a pull request? Then we can talk about it during Triage Tuesday.

[qqmyers]

FYI - please see #11685 - this is an odd issue (thanks for reporting!) that I think was fixed once an has reappeared (!). My suggestion in #11685 is to force the values to be sorted as required rather than adding a fake date.