CI: Fix aarch64 builds on x86 after switching to role

bf04bd90a15e7d3949214d15a8b8e25f2050bb65 omitted the --platform
option

Change-Id: I4febdf6b391bb7320ea30e1ca71fed81e332021d

.zuul.d/centos.yaml

@@ -23,6 +23,8 @@
     name: kolla-build-centos9s-aarch64
     parent: kolla-build-centos9s
     nodeset: kolla-centos-9-stream
+    vars:
+      base_arch: aarch64
     voting: false
 
 - job:

.zuul.d/rocky.yaml

@@ -70,6 +70,8 @@
     name: kolla-build-rocky9-aarch64
     parent: kolla-build-rocky9
     nodeset: kolla-rockylinux-9
+    vars:
+      base_arch: aarch64
     voting: false
 
 - job:

.zuul.d/ubuntu.yaml

@@ -70,6 +70,8 @@
     name: kolla-build-ubuntu-aarch64
     parent: kolla-build-ubuntu
     nodeset: kolla-ubuntu-noble
+    vars:
+      base_arch: aarch64
     voting: false
 
 - job:

roles/kolla-build/tasks/main.yml

@@ -12,5 +12,7 @@
       --work-dir {{ kolla_build_logs_dir }}/work_dir
 
 - name: Run kolla-build
+  vars:
+    platform: "{{ '--platform linux/arm64' if base_arch == 'aarch64' and base_arch != ansible_facts.architecture }}"
   ansible.builtin.command:
-    cmd: "{{ kolla_build_venv_path }}/bin/kolla-build"
+    cmd: "{{ kolla_build_venv_path }}/bin/kolla-build {{ platform }}"