Use memory_store for cache in CI

.circleci/config.yml

@@ -15,7 +15,6 @@ executors:
           SOLR_URL: http://solr:SolrRocks@localhost:8983/solr/orangelight-core-test
           COVERALLS_PARALLEL: true
           VITE_RUBY_AUTO_BUILD: false
-          MEMCACHED: memcached
       - image: cimg/postgres:15.8
         environment:
           POSTGRES_USER: orangelight
@@ -24,11 +23,6 @@ executors:
       - image: pulibrary/ci-solr:8.4-v1.0.0
         command: server/scripts/ci-start.sh
       - image: cimg/redis:6.0.16
-      - image: memcached
-        command:
-        - --conn-limit=1024
-        - --memory-limit=64
-        - --threads=4
     resource_class: large
     working_directory: ~/orangelight
   basic-executor:

config/environments/test.rb

@@ -18,7 +18,8 @@
   # your test database is "scratch space" for the test suite and is wiped
   # and recreated between test runs. Don't rely on the data there!
   config.cache_classes = true
-  config.cache_store = :mem_cache_store, "#{ENV['lando_orangelight_memcached_conn_host']}:#{ENV['lando_orangelight_memcached_conn_port']}" || ENV['MEMCACHE_SERVERS'] # Will fallback to $MEMCACHE_SERVERS, then 127.0.0.1:11211
+  # use null_store in CI, mem_cache_store locally
+  config.cache_store = ENV['CI'].present? ? :memory_store : :mem_cache_store, "#{ENV['lando_orangelight_memcached_conn_host']}:#{ENV['lando_orangelight_memcached_conn_port']}"
 
   # Eager loading loads your whole application. When running a single test locally,
   # this probably isn't necessary. It's a good idea to do in a continuous integration