Update TestEval  test case "split"

TestEval "split" is broken. We should fix or remove.

```
    eval_test.go:172: Eval() got error = failed to evaluate: invalid operation: int(string) (1:14)
         | object.image.split(':').size() == 2
         | .............^, wantErr false
    --- FAIL: TestEval/split (0.00s)
```