test/e2e/apps: Add missing wait for pods readiness in sts test

During testing recreate strategy we are injecting a broken image to fail
the entire statefulset. After that we're updating the statefulset with
correct one and expect the controller correctly recreates pods. The
problem was that we only waited for status.observedGeneration to catch
up but not for pods, which in the next steps we iterated over and
checked for updated image. Adding WaitForRunningAndReady, similarly how
we do that early on in the test should resolve the problem.

Signed-off-by: Maciej Szulik <soltysh@gmail.com>