We should run the self-tests before using jstestfuzz on Evergreen.

Tasks:
1 - Split out the 'npm install' step into a separate command that fails if dependencies fail to install, this way the failure is indicated as a system failure instead of a test failure

2 - Remove some of the fail-safe code we have to handle npm issues (e.g., npm install || true -> npm install)

3 - Run 'npm test' as a "test" command to run the jstestfuzz unit tests before running 'npm start'