sap_ha_pacemaker_cluster: stonith location constraints

[ja9fuchs]

• Moved default stonith setup into a block to share conditionals.
• Removed 1 block conditional which is not needed for the block that only applies when the role platform defaults are used.

New task
Adding default location constraints when fence resources are defined per host.
This prevents per-host fence resources from running on the same, targeted node.

Currently GCP has a default stonith definition that works this way.

Result on GCP:

Location Constraints:
  resource 'rsc_fence_gce_hana01' avoids node 'hana01' with score INFINITY
  resource 'rsc_fence_gce_hana02' avoids node 'hana02' with score INFINITY

  * rsc_fence_gce_hana01        (stonith:fence_gce):     Started hana02
  * rsc_fence_gce_hana02        (stonith:fence_gce):     Started hana01

Tested (on RHEL)
GCP: correct default resource and constraints configuration
AWS: runs the default fence resource task, then skips the constraints task as expected

Reference
https://cloud.google.com/solutions/sap/docs/sap-hana-ha-config-rhel#create_the_fencing_device_resources

[marcelmamula]

LGTM. Naming could be improved, but it works.
Tested on SLES4SAP 15 SP6 on GCP.