Correct closed widget tooltip display format

What does this MR do and why?

For #539203 (closed)

Updates the render of the date time tooltip in the MR Status ("Closed") Widget on the MR Overview tab to match the display elsewhere in the app and - notably - in the MR Commits tab.

References

• !211668 (closed)
• !211831 (merged)

Screenshots or screen recordings

The datetime tooltip display on the Commits tab looks like this, for reference:

Here's the Overview tab Closed widget:

Before	After

How to set up and validate locally

1. You will need an MR with at least 1 commit.
2. Close the MR.
3. See the tooltip datetime format in the Overview tab for the Closed MR status widget. Compare to the format on the Commits tab for an individual commit.

MR acceptance checklist

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