first_seen date should not depend on nickname changes

I was checking which relays joined the network yesterday (2024-06-09) and got (among other things) the following data back from our database:

| 2A23ACF28A1D41D7E7C2BC27B96B3F99E6333E87 | 1KohW9VnCMhyd                            | 2024-06-09 01:00:00  | l3y6aetzp7mnnzwafavrwfwjwupryr72gatp77c4yzeavinozgdgppad.onion | None                                               | Tor 0.4.8.12    |
| 2A23ACF28A1D41D7E7C2BC27B96B3F99E6333E87 | esYyzm2hzkIBO                            | 2024-06-09 22:00:00  | l3y6aetzp7mnnzwafavrwfwjwupryr72gatp77c4yzeavinozgdgppad.onion | None                                               | Tor 0.4.8.12    |
| 2A23ACF28A1D41D7E7C2BC27B96B3F99E6333E87 | vMSk3VJ5jwXDE                            | 2024-06-09 18:00:00  | l3y6aetzp7mnnzwafavrwfwjwupryr72gatp77c4yzeavinozgdgppad.onion | None                                               | Tor 0.4.8.12    |
| 2A23ACF28A1D41D7E7C2BC27B96B3F99E6333E87 | zxLnaDJsOTTKK                            | 2024-06-09 02:00:00  | l3y6aetzp7mnnzwafavrwfwjwupryr72gatp77c4yzeavinozgdgppad.onion | None                                               | Tor 0.4.8.12    |

So, the same relay (2A23ACF28A1D41D7E7C2BC27B96B3F99E6333E87) joined four times for the first time yesterday. That's... odd. The expected result would be only entries with 2024-06-09 01:00:00 (if there are supposed to be many anyway to begin with) or no entries at all, in case it actually joined earlier (say, 2024-06-08 23:00:00).