compute pods replica based on ha mode

What does this MR do and why?

changes in .Values._internal.ha_cluster:

• introduce a new boolean value .Values._internal.ha_cluster.is_ha
• remove value .Values._internal.ha_cluster.mode

improvement:

• force is_ha to False in the bootstrap.values.yaml in order to force replicaset to 1
• force checkpoint to null in bootstrap.values.yaml in order to prevent any verifications (typically in bootstrap with is_ha=False + control_plane_replicas=3)
• change in .Values._internal.ha_cluster.checkpoint in order to avoid issue in bootstrap when Helmrelease sylva-units is patched with capo-cluster-resources values (without this fix, the patch is seen as an upgrade with is_ha moved from False to True which is forbidden)

use this .Values._internal.ha_cluster.is_ha with ternary operator to compute pod replicas or pod disruption budget whenever it is possible

Related reference(s)

closes #902 (closed) closes #1162 (closed)