Generate and upload code coverage report for operator-developer-e2e job

[m1kola]

We currently have 2 jobs which upload code coverage to codecov:

• unit-test
• e2e

But we also have operator-developer-e2e which was added more recently and it does not upload coverage.

We should consider uploading code coverage from this job as well to have more complete picture.

[m1kola]

#441 adds codecov.yml which tells codecov how many jobs it should wait for before sending notifications.

If as part of this issue we add a new job - the number will need to be incremented.

[trgeiger]

/assign