[ci_gen_kustomize_values] Fix 3-run death spiral in edpm-nodeset2-values template

The edpm-nodeset2-values template derives _vm_type by splitting the first
node name from the existing values.yaml (e.g. edpm-compute-0 -> compute).
It then uses _vm_type to find matching instances (startswith compute2-).

This creates a self-poisoning 3-run death spiral:

Run 1: nodes have git placeholder names (edpm-compute-0)
       -> _vm_type=compute -> finds compute2-* instances -> writes real
          hostnames (edpm-compute2-XXXXX-0) back to values.yaml

Run 2: nodes now have real CI hostnames (edpm-compute2-XXXXX-0)
       -> _vm_type=compute2 -> searches for compute22-* (does not exist)
       -> instances_names=[] -> writes nodes: null back to values.yaml

Run 3: nodes is null (Python None)
       -> None | default({}) returns None (default only fires for Undefined)
       -> None.keys() -> CRASH: None has no attribute keys

Fix with two changes:
1. Replace | default({}) with explicit None-safe conditional so that
   an explicit YAML null does not sneak through as Python None.
2. Strip trailing digits from the derived _vm_type so that after run 1
   rewrites node names, compute2 strips back to compute and the instance
   lookup continues to find compute2-* entries correctly on all subsequent
   runs.

Signed-off-by: Ade Lee <alee@redhat.com>
Co-Authored-By: Claude <noreply@anthropic.com>

Author: 2 people

roles/ci_gen_kustomize_values/templates/multi-namespace/edpm-nodeset2-values/values.yaml.j2

@@ -3,9 +3,9 @@
 {% set _ipv = cifmw_ci_gen_kustomize_values_ip_version_var_mapping                        %}
 {% set instances_names = []                                                               %}
 {% set _original_nodeset = (original_content.data | default({})).nodeset | default({})    %}
-{% set _original_nodes = _original_nodeset.nodes | default({})                            %}
+{% set _original_nodes = _original_nodeset.nodes if _original_nodeset.nodes else {}       %}
 {% set _original_services = _original_nodeset['services'] | default([])                   %}
-{% set _vm_type = (_original_nodes.keys() | first).split('-')[1]                          %}
+{% set _vm_type = ((_original_nodes.keys() | first).split('-')[1] | regex_replace('\\d+$', '')) if _original_nodes else 'compute' %}
 {{ '#vmtype: ' ~ _vm_type }}
 {% for _inst in cifmw_networking_env_definition.instances.keys()                          %}
 {%   if _inst.startswith(_vm_type ~ "2-")                                                 %}