Summary:
This should be more robust across MacOS and Linux.
Closes #388
Fixes #306

Test Plan: Ran the scripts, ensured that the generated secrets look correct.

Reviewers: zasgar, michelle

Reviewed By: michelle
Signed-off-by: Frederick Ryckbosch <fryckbosch@newrelic.com>

Differential Revision: https://phab.corp.pixielabs.ai/D10474

GitOrigin-RevId: 846d451eb0e70b9d4478bd389fbdab8925c5f00e