Fix a test related to cyclic import error

[xin-tsla]

TDLR: In the PR https://github.com/golang/go/pull/68337, we added more info in the error stack, it needs a change in x/tools'test too. Before: golang.org/fake/a golang.org/fake/b golang.org/fake/a After: golang.org/fake/a golang.org/fake/b from a.go golang.org/fake/a from b.go