Eliminate EJR queries from batch job context?

[soxofaan]

We're currently experiencing problems with failing batch job due to EJR availability. Each batch job does a health check request to the EJR, which now fails often. In the majority of batch jobs however, the EJR is actually not necessary, so this failing health check is an unnecessary cause of failure.

As far as we identified, the EJR dependency from within batch jobs is to handle a user's own, but unsigned batch job result URL: ba1135a#diff-aaeea51041d5a176c49b2dc6069775385a54ce83e97193ea95f87e3aea3c08df for #792

[soxofaan]

I'm now working on a quickfix to turn off the health check from batch job context.
Note that in other contexts (web app, job tracker) this health check is still useful to fail fast on misconfiguration, so I'll keep it on by default

[soxofaan]

Next step: fully eliminate the dependency on EJR from batch jobs (not only to improve stability, but also security).
The original "handle a user's own, but unsigned batch job result URL" problem could for example be solved before submitting the batch job