TMDM-6962: "Investigate if "isEmptyOrNull" can be equivalent to "is empty list" on repeatable elements"

Add unit test to test feature.
Fix isEmpty support when repeatable field is at depth > 1 in record.
IsNull on a repeatable field is now considered same as IsEmpty.
(https://jira.talendforge.org/browse/TMDM-6962)
(cherry pick from e4793df60aa2d4ba585bc642f5f4e1f6e4f70a69)