[token-server] Tighten rate limits

Summary:
Initially liked leaving the door open to users "gaming" this a bit, i.e. getting multiple manual claims. If they are really manual, it's not really a big deal -- implies someone wants to make another tx.

In practice though we are seeing scripts get most of the rewards. So, tighten it up.

Test Plan: npm test

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D16764