pm: ticket redemption race condition leads to not properly setting fields in DB that mark the ticket as redeemed

[kyriediculous]

Describe the bug
After receiving a winning ticket and popping it from the ticketQueue there was a race condition that tried to redeem the winning ticket twice within the same block.

This caused the redeemedAt and txHash fields to not be set within the database and this winning ticket to be retried over and over.

While this issue would be fixed by #1598 which prevents redeeming used tickets and marks them as redeemed, that PR does not fix the race condition that occured here.

• Succesful transaction: https://etherscan.io/tx/0x5313a08086831582a737e7f4486fce78c9beb2c26e5b8a592fab95fc1a63f714
• Failing transaction: https://etherscan.io/tx/0x6ecc25bcf006710ba99ca9fd0af9146acbaa305555b157dddda95e55ccea4f07

Expected behavior
To only send a single transaction for a winning ticket