DEV: s/\$redis/Discourse\.redis

With manual merge conflicts

spec/support/shared_examples_for_stats_cacheable.rb

@@ -3,19 +3,19 @@
 shared_examples_for 'stats cachable' do
   describe 'fetch_cached_stats' do
     after do
-      $redis.del(described_class.stats_cache_key)
+      Discourse.redis.del(described_class.stats_cache_key)
     end
 
     it 'returns the cached stats' do
       stats = described_class.fetch_stats.to_json
-      $redis.set(described_class.stats_cache_key, stats)
+      Discourse.redis.set(described_class.stats_cache_key, stats)
       expect(described_class.fetch_cached_stats).to eq(JSON.parse(stats))
     end
 
     it 'returns fetches the stats if stats has not been cached' do
       freeze_time
 
-      $redis.del(described_class.stats_cache_key)
+      Discourse.redis.del(described_class.stats_cache_key)
       expect(described_class.fetch_cached_stats).to eq(JSON.parse(described_class.fetch_stats.to_json))
     end
   end