[Bug-Candidate]: Maximize CPU output when running fuzzer

### Describe the issue:

When deployed on a 16 core machine, with 15 workers, the CPU usage seems to be maxed at about 40-50%. When deployed on an 8 core machine, with 7 workers, CPU usage has only ever hit a max of around 65%.

### Code example to reproduce the issue:

Follow instructions for reproduction here, and if testing on cloudexec, then run `make ec` (for echidna-cloud) or `make el` (echidna-local).

https://github.com/curvance/Curvance-CantinaCompetition/tree/CodeFAQAndAdjustments/tests/fuzzing

### Version:

Echidna 2.23 & previous

### Relevant log output:

_No response_

Follow the linked Curvance-CantinaCompetition fuzzing reproduction and run it with `make ec` or `make el`, comparing CPU usage on the stated worker and core counts. Read the relevant Echidna execution path to identify why utilization remains below the available CPU capacity; done means the fuzzer uses substantially more of the available cores under these reproductions.

Written by the indexing model from the issue text.