[token-server] Reduce faucet reward

Summary:
Some kind of script is going through the 30xec rewards. need to get some countermeasures together.

for starters, reduce the reward.

Test Plan: npm test

Reviewers: #bitcoin_abc, johnkuney

Reviewed By: #bitcoin_abc, johnkuney

Differential Revision: https://reviews.bitcoinabc.org/D16680