test: Extend Spark Array functions: array_repeat , shuffle and slice test coverage

[erenavsarogullari]

Which issue does this PR close?

• Closes Extend Spark Array functions: array_repeat , shuffle and slice test coverage #20419.

Rationale for this change

This PR adds new positive and negative test cases for datafusion-spark array functions: array_repeat , shuffle, slice for the following use-cases:

- nested function execution,
- invalid parameter settings to verify validation,
- different datatypes such as timestamp,
- casting before function execution

Also, being updated contributor-guide testing documentation with minor addition.

What changes are included in this PR?

Being added new positive and negative test cases to datafusion-spark array functions: array_repeat , shuffle, slice.

Are these changes tested?

Yes, adding new positive and negative test cases.

Are there any user-facing changes?

No