cmd/go: unclear when packages have missing test coverage with 1.22

### Go version

go1.22rc1 darwin/amd64

### Output of `go env` in your module/workspace:

```shell
N/A
```


### What did you do?

Created a go file with a couple of interfaces with some method signatures and a variable declaration only

### What did you see happen?

[no test files]

### What did you expect to see?

coverage: 0.0% of statements