reload HAProxy config in HA setups when certificate is updated

reload HAProxy config in HA setups when certificate is updated

When updating a certificate for HAProxy, we only do a reload of the
configuration on non-HA setups. This means that if we try the same in
an HA setup, the cloud will still serve the old certificate and that
leads to several issues, such as serving a revoked or even a
compromised certificate for some time, or just SSL issues that the
certificate doesn't match. This enables a reload for HA cases too.

Change-Id: Ib8ca2fe91be345ef4324fc8265c45df8108add7a
Closes-Bug: #1629886