Use let_it_be instead of let in Pipeline test

What does this MR do and why?

I noticed that we don't use let_it_be for creating pipeline in ee/spec/models/ci/pipeline_spec.rb so I fixed it. I added refind option, as one of the test failed. As well, I've changed let to let_it_be in dependency_list_reports as that was my initial goal.

with let

Finished in 42.68 seconds (files took 17.48 seconds to load)
127 examples, 0 failures

[TEST PROF INFO] Time spent in factories: 00:27.495 (61.93% of total time)

with let_it_be

Finished in 37.79 seconds (files took 11.67 seconds to load)
127 examples, 0 failures

[TEST PROF INFO] Time spent in factories: 00:24.414 (63.34% of total time)

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