Add e2e tests for `shp buildrun gather`

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Kubernetes Version

_No response_

### Shipwright Version

_No response_

### Current Behavior

since PR #380 is merged, e2e tests for `shp buildrun gather` needs to be added

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Anything else?

_No response_