Try libeatmydata in edx-platform tests

libeatmydata speeds up disk writes by turning off fsync functionality; this increases the risk of data loss on crashes, but this is a negligible risk when running tests (crashes are rare and typically cause the tests to fail anyway).

A/C:

• Review New Relic Infrastructure metrics to identify the processes which write the most data to disk during edx-platform test jobs (npm, pip, MySQL, and MongoDB are likely candidates).

• Install libeatmydata on the AMIs used to run tests

• Try enabling libeatmydata for the target processes and measure the impact (if any) on job duration.