`policy_options`: changes to the nren communities calculation

If NREN custom ASN is defined for LHCONE, use it for the _BLOCK
community; skip the NREN community.

geant/gap_ansible/roles/policy_options/tasks/calc_nren_communities.yaml

 ---
+# When custom ASN is defined in partner general.yaml inventory for LHCONE,
+# this is used for only _BLOCK community to configure, the GEANT_<NREN>
+# community will stay standard with the standard partner's ASN.
+#
 - name: Set NREN community names
   when: not subscription.product.product_type | upper  in ['LHCONE']
   ansible.builtin.set_fact:
@@ -6,18 +10,42 @@
 
 - name: Set NREN community names
   when: subscription.product.product_type | upper  in ['LHCONE']
-  ansible.builtin.set_fact:
-    nren_community_names: ["GEANT_{{ partner_name | upper }}", "LHCONE_{{ partner_name | upper }}_BLOCK"]
+  block:
+    - name: Set standard NREN community names
+      when: not partner[subscription.product.product_type | upper].asn is defined
+      ansible.builtin.set_fact:
+        nren_community_names: ["GEANT_{{ partner_name | upper }}", "LHCONE_{{ partner_name | upper }}_BLOCK"]
 
-- name: Set NREN community values (2-byte ASN)
-  when: (partner.asn | int) < 65536
-  ansible.builtin.set_fact:
-    nren_community_values: ["{{ geant_re_as_number }}:{{ partner.asn }}", "{{ bgp.block_community_prefix }}:{{ partner.asn }}"]
+    - name: Set custom NREN community names
+      when: partner[subscription.product.product_type | upper].asn is defined
+      ansible.builtin.set_fact:
+        nren_community_names: ["LHCONE_{{ partner_name | upper }}_BLOCK"]
 
-- name: Set NREN community values (4-byte ASN)
-  when: (partner.asn | int) > 65535
-  ansible.builtin.set_fact:
-    nren_community_values: ["origin:{{ partner.asn }}:{{ geant_re_as_number }}", "origin:{{ partner.asn }}:{{ bgp.block_community_prefix }}"]
+- name: Set NREN communities values using "partner.asn"
+  when: not partner[subscription.product.product_type | upper].asn is defined
+  block:
+    - name: Set NREN community values (2-byte ASN)
+      when: (partner.asn | int) < 65536
+      ansible.builtin.set_fact:
+        nren_community_values: ["{{ geant_re_as_number }}:{{ partner.asn }}", "{{ bgp.block_community_prefix }}:{{ partner.asn }}"]
+
+    - name: Set NREN community values (4-byte ASN)
+      when: (partner.asn | int) > 65535
+      ansible.builtin.set_fact:
+        nren_community_values: ["origin:{{ partner.asn }}:{{ geant_re_as_number }}", "origin:{{ partner.asn }}:{{ bgp.block_community_prefix }}"]
+
+- name: Set NREN communities values using {{partner[subscription.product.product_type | upper]}}.asn
+  when: partner[subscription.product.product_type | upper].asn is defined
+  block:
+    - name: Set NREN community values (2-byte ASN)
+      when: (partner[subscription.product.product_type | upper].asn | int) < 65536
+      ansible.builtin.set_fact:
+        nren_community_values: ["{{ bgp.block_community_prefix }}:{{ partner[subscription.product.product_type | upper].asn }}"]
+
+    - name: Set NREN community values (4-byte ASN)
+      when: (partner[subscription.product.product_type | upper].asn | int) > 65535
+      ansible.builtin.set_fact:
+        nren_community_values: ["origin:{{ partner[subscription.product.product_type | upper].asn }}:{{ bgp.block_community_prefix }}"]
 
 - name: Create a list of NREN communities
   ansible.builtin.set_fact: