the e2e framwork use active loops to wait for certain async operations,
these loops need to retry on some operations and fail in others.
For the functions that depend on some operations to happen, the
apiserver may return 503 errors until that specific service is
available, so we should retry on those too.
Change-Id: Ib3d194184f6385b9d3d151c7055f27c97c21c3ff
These helper functions can be used in combination with
omega.Eventually/Consistently to implement polling of objects that is aware of
Kubernetes apiserver conventions:
- retry on certain errors instead of giving up,
with "not found" handling decided by the caller (may or may not
be fatal, depending on the test)
- sleep if requested by apiserver
