e2e test script problems when running locally

[aliok]

Problems:

1. OPERATOR_DIR is a relative path only and that results in strange behavior later, when we cd back, we won't actually cd back.
2. ko resolve -P should only be used in prow, when targeting GCR. When targeting DockerHub (as when running the tests locally for example), I can't use -P since DockerHub doesn't support nested paths. UPDATE: I switched to using Quay.io and I will ignore this problem for now.

Original: houshengbo#1

[aliok]

/assign @aliok