DJ repo: Error removing job 0 on scheduler delete

Since we pulled new DJ milestone (opendj-server-7.0.0-M2019-9.5.zip) in this commit one of our tests started to fail with

WARNING: Resource exception: 500 Internal Server Error: "Error removing job 0"

Full stack trace attached.

I couldn't manually reproduce the issue.

The steps in the test are following:

• create 10 schedulers which are not enabled
• then turn all of them ON at the same time
• let them run for some time (let them fire few times)
• then delete them over the rest (scheduler/job/${scheduler_id})

To run the automated test:

./run-pybot.py -t concurrent_enable_should_not_throw_PreconditionFailedException -n openidm