Niad-3407: Remove usages of Mockito.lenient() in test suite

[Jonopono123]

What

There are numerous usages of Mockito.lenient() in the codebase. These need to be removed.

Why

Using Mockito.lenient() in this way covers up any dependency related issues in our tests, reducing their reliability.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Internal change (non-breaking change with no effect on the functionality affecting end users)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have performed a self-review of my code
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes

[github-actions]

Looks good. No mutations were possible for these changes.
See https://pitest.org

[github-actions]

Images built and published to ECR using a Build Id of PR-910-e74e91b