Porting legacy tests from ".Flow/flow" — test case "should not be able to access values set in a flow across different flows"

link [should not be able to access values set in a flow across different flows](https://github.com/rainlanguage/rain-protocol/blob/7f0b708db67001e7dc8122de8a901398ea92a2f3/test/Flow/Flow/flow.ts#L1604)