Figure out why server descriptor observed bandwidth is not seen for at least 4 days by some bwauths

One reason could be that at the moment of the measurement, sbws can't see it. Other could be that when the measurement fails, the original data structures doesn't store that moment observed bandwidth. I think i created an issue for this last one that at that moment didn't look important and it doesn't happen in onbasca. Maybe it's one of these: https://gitlab.torproject.org/tpo/network-health/sbws/-/issues/?sort=updated_desc&state=closed&search=observed&first_page_size=100

Maybe #40190 (moved) could be happening due this too (observed getting higher and sbws taking days to realize)