Instrument e2e pipelinerun_test.go files for logstream

These two (`test/pipelinerun_test.go` and `test/v1alpha1/pipelinerun_test.go`)
weren't done in the last PR, because they were messy and I wanted to get that PR
in. But I had some time this morning, so here they are, which should be the last
things in the e2e tests (other than examples/yamls testing, which are their own
bucket of worms) to be instrumented with `helpers.ObjectNameForTest(t)`.

Signed-off-by: Andrew Bayer <andrew.bayer@gmail.com>