Differentiate when a slow zone is brand new versus when one reappears

[nathan-weinberg]

In the event where the T "fixes" a slow zone but we see it reappear within a "to be determine" amount of time. Rather than calling it out as new, we should highlight that this is something that was fixed but has reappeared.

This could be done by checking for the same group of stops pairs and seeing if it recently existed based off whatever length of time we feel is appropriate.