Assert the job is running in the test_e2e

[FlorentClarret]

What does this PR do?

Add an assert to the mapreduce test_e2e.

Motivation

This test is failing sometimes. Example:

• https://dev.azure.com/datadoghq/integrations-core/_build/results?buildId=106873&view=logs&jobId=44f80fa8-59b4-5eac-d564-3b72739a148c&j=44f80fa8-59b4-5eac-d564-3b72739a148c&t=37cf5e0d-a62f-5d05-e6eb-b5df035c1060

I'm not sure if this is because the mapreduce.job.elapsed_time.max is optional or if it's because the job is not running. I think it is the latter. Adding an assert will let us know if the job is running or not before running the check and assert the metrics are well collected.

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] PR title must be written as a CHANGELOG entry (see why)
• [ ] Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• [ ] PR must have changelog/ and integration/ labels attached

[codecov[bot]]

Codecov Report

Merging #12686 (b8f5a5f) into master (052c358) will not change coverage. The diff coverage is 0.00%.

Flag	Coverage Δ
mapreduce	81.77% <0.00%> (ø)

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