CLOUDP-279474: Use generator to avoid sharing list value

[josvazg]

• 1st commit adds a test to detect the race condition.
• 2nd commit fixes the race condition by using a function that generates the empty list for each call, instead of reusing the same value for all calls.

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https://app.codecov.io/github/mongodb/mongodb-atlas-kubernetes/commit/4e26fb69e2a9f7f2af0f8e0712b623eee40a7f61