NIFI-6401 - Long List of Users Overflows onto Date

[rfellows]

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Description of PR

This fixes a display issue when viewing the list of users. If the list was very long (or the browser very short) the user list would overlap the Date/time display at the bottom.

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[mcgilman]

Will review...

[mcgilman]

Thanks @rfellows! This has been merged to master.