Move CLAMP Storage access to RWO

Move CLAMP Storage access to RWO

Today when deploying CLAMP with OOM, the PersistentVolumeClaim needs the
"ReadWriteMany" (or "RWX") capability.

According to Kubernetes Documentation (https://kubernetes.io/docs/concepts/storage/persistent-volumes/#access-modes),
ReadWriteMany stands for "the volume can be mounted as read-write by many nodes".

That means that a particular PVC needs to be read and written from many pods.
That also means that your code takes that into account and do the work to avoid
write at the same place at the same time.

An issue on RWX mode is that most "official" storage driver from Kubernetes doesn't
support it (13 over the 19 drivers doesn't support it, espacially OpenStack, Amazon
and Google storage classes).

CLAMP PVC is used only for one ES instance. Thus we don't need RWX.

Change-Id: I3a17195bca4f0f01b5cdb0d8e803bb2a8ab2dd38
Issue-ID: CLAMP-488
Signed-off-by: Sylvain Desbureaux <sylvain.desbureaux@orange.com>