"Most recent activity" should be day-based

Description

The current calculation of the "x days ago" field seems to take into account the time of day. This seems to me like unwanted behaviour as I quite frequently get results like this, where commits from the same day show up as two different days.

Proposal

For the "x days ago" calculation, only the date component should be used. Even for multi-timezone teams, having the date jump at a predictable time of day (server local midnight for example) rather than the current time should give much more consistent and workable results.

Use cases

Me looking at what I did 3 days ago so I can write a report on it, and saving tons of annoyance when hovering over fields.

Alternative proposal

Show more info (like commit message) when clicking on a date in the top graph. Currently it just shows "pushed to branch XYZ" which is not really helpful most of the time (especially if corporate forces you to do workflows outside of gitlab, like not having your issues there).