Revert "[travis] Enable stack traces in the container"
Revert "[travis] Enable stack traces in the container"

This reverts commit c9771f2b97b764ed5e188055f93c151f7df151ec.
The targeted docker configuration was not working with travis' old version of docker.

fire-rs-laas/fire-rs-saop,fire-rs-laas/fire-rs-saop,fire-rs-laas/fire-rs-saop,fire-rs-laas/fire-rs-saop