Fix duplicate rows in /coins if multiple reward pool accounts

[dharit-tan]

• I accidentally created a non-ATA account on the authority of PHUTURES
• Later created the ATA
• /v1/coins was giving duplicate rows for PHUTURES
• Fix by only selecting earliest-created account for that owner - as a proxy for the ATA, assuming we'd create it as part of the reward pool creation process.
• But technically the PHUTURES response is still showing the wrong account (since I created the non-ATA before the ATA). Not a huge issue bc we don't use that value anywhere. But maybe I can just delete that row for this case?

Tested on prod

[rickyrombo]

This works, but yeah I think we just delete the row we don't care about