Fix line delimited JSON response

For GET /events, line delimit JSON.
Fixes #7047

Signed-off-by: Jessica Frazelle <jfrazelle@users.noreply.github.com>
I'm not sure that cli tests is place for doing such things. We definitely need api tests, but we have no still :) This possibly could be tested in events unit_tests by creating fake `job` and adding connecting pipe to stdout.