Bugfix: scope vulnerability occurrences by Time not Date

What does this MR do?

Fix scoping issue on Vulnerabilities::Occurrence where period is rounded by Date instead of Time. This can lead to edgecase failures on machines that do not have TZ set to UTC.

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
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