Add another instance / increase spammer capacity

[nrutledge]

The transaction throughput is low according to Maxim. To resolve this (and to more accurately simulate a real network), we should add at least one more instance (Cardano node + tx spammer).

We can spin up another Digital Ocean droplet for this, but it should have at least 24 GB of RAM and 4 vCPUs as per Maxim.

More details on Slack: https://mlabs-corp.slack.com/archives/C0602K159NU/p1710778019245429