Way of Testing tkn task start -t

[danielhelfand]

/area testing

Currently, tkn task start features a --timeout or -t flag that allows a user to set the timeout for a task run. While the unit test case of actually setting the property is covered, it would be nice to have some sort of test that covers the case of setting the timeout to a value besides the default and testing if a task run times out appropriately. Testing this as an e2e case I think would be the way to go.