FIX: add support for pipelined and multi redis commands (#16682)

Latest redis interoduces a block form of multi / pipelined, this was incorrectly
passed through and not namespaced.

Fix also updates logster, we held off on upgrading it due to missing functions

app/services/random_topic_selector.rb

@@ -40,9 +40,9 @@ class RandomTopicSelector
     key = cache_key(category)
 
     if results.present?
-      Discourse.redis.multi do
-        Discourse.redis.rpush(key, results)
-        Discourse.redis.expire(key, 2.days)
+      Discourse.redis.multi do |transaction|
+        transaction.rpush(key, results)
+        transaction.expire(key, 2.days)
       end
     end
 
@@ -56,9 +56,9 @@ class RandomTopicSelector
 
     return results if count < 1
 
-    results = Discourse.redis.multi do
-      Discourse.redis.lrange(key, 0, count - 1)
-      Discourse.redis.ltrim(key, count, -1)
+    results = Discourse.redis.multi do |transaction|
+      transaction.lrange(key, 0, count - 1)
+      transaction.ltrim(key, count, -1)
     end
 
     if !results.is_a?(Array) # Redis is in readonly mode