Update TestValidation/Homogeneous_Aggregate_Validation_test_5

[polds]

TestValidation/Homogeneous_Aggregate_Validation_test_5 is broken. We should fix or remove.

=== RUN   TestValidation/Homogeneous_Aggregate_Validation_test_5
    eval_test.go:353: Compile() got error = unexpected token Operator("?") (1:19)
         | name in ['hello', ?optional.ofNonZeroValue('')]
         | ..................^, wantErr false
    --- FAIL: TestValidation/Homogeneous_Aggregate_Validation_test_5 (0.00s)