[stable/2023.2] fix: memcached and memcachedExporter use the atmosphere_images (#1888)

This is an automated cherry-pick of #1885
/assign mnaser
diff --git a/roles/loki/vars/main.yml b/roles/loki/vars/main.yml
index ff6268d..f305e49 100644
--- a/roles/loki/vars/main.yml
+++ b/roles/loki/vars/main.yml
@@ -37,6 +37,14 @@
           index:
             prefix: index_
             period: 24h
+  memcached:
+    image:
+      repository: "{{ atmosphere_images['memcached'] | vexxhost.kubernetes.docker_image('name') }}"
+      tag: "{{ atmosphere_images['memcached'] | vexxhost.kubernetes.docker_image('tag') }}"
+  memcachedExporter:
+    image:
+      repository: "{{ atmosphere_images['prometheus_memcached_exporter'] | vexxhost.kubernetes.docker_image('name') }}"
+      tag: "{{ atmosphere_images['prometheus_memcached_exporter'] | vexxhost.kubernetes.docker_image('tag') }}"
   test:
     enabled: false
   singleBinary: