In some cases (CI) it is useful to run NFD e2e tests using
ephemeral clusters. To save time and bandwidth, it is also useful
to prime the ephemeral cluster with the images under test.
In these circumstances there is no risk of running a stale image,
and having a `Always` PullPolicy hardcoded actually makes
the whole exercise null.
So we add a new option, disabled by default, to make the e2e
manifest use the `IfNotPresent` pull policy, to effectively
cover this use case.
Signed-off-by: Francesco Romani <fromani@redhat.com>
