LOCALISATION_JOB: ERT fails if all observations belonging to a correlation group (ministep) is deactivated

[oddvarlia]

Describe the bug
ERT fails with an error if all observations belonging to a ministep (specified correlation group in localisation config file) is deactivated.

To Reproduce
Steps to reproduce the behavior:

1. Define a model with non-adaptive localisation (using the LOCALISATION_JOB)
2. All observations in a correlation group must be deactivated as outliers

Expected behavior
The creation of the ministep belonging to the correlation group must be skipped and a warning that this is done due to no active observations belonging to the correlation group.

Screenshots
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Additional context
This problems is very similar to issue number 498