Revert "DEV: Upgrade Redis to 4.8" (#18099)

This reverts commit 0b5a0fd857.

Pending release of Sidekiq 6.5.6 so that we don't get depreciation
warnings

Gemfile.lock

@@ -229,7 +229,7 @@ GEM
     logstash-event (1.2.02)
     logstash-logger (0.26.1)
       logstash-event (~> 1.2)
-    logster (2.11.3)
+    logster (2.11.2)
     loofah (2.18.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
@@ -375,7 +375,7 @@ GEM
       msgpack (>= 0.4.3)
       optimist (>= 3.0.0)
     rchardet (1.8.0)
-    redis (4.8.0)
+    redis (4.7.1)
     redis-namespace (1.9.0)
       redis (>= 4)
     regexp_parser (2.5.0)
@@ -643,4 +643,4 @@ DEPENDENCIES
   yaml-lint
 
 BUNDLED WITH
-   2.3.20
+   2.3.18

lib/discourse_redis.rb

@@ -50,8 +50,8 @@ class DiscourseRedis
    :hdel, :hexists, :hget, :hgetall, :hincrby, :hincrbyfloat, :hkeys, :hlen, :hmget, :hmset, :hset, :hsetnx, :hvals, :incr,
    :incrby, :incrbyfloat, :lindex, :linsert, :llen, :lpop, :lpush, :lpushx, :lrange, :lrem, :lset, :ltrim,
    :mapped_hmset, :mapped_hmget, :mapped_mget, :mapped_mset, :mapped_msetnx, :move, :mset,
-   :msetnx, :persist, :pexpire, :pexpireat, :psetex, :pttl, :rename, :renamenx, :rpop, :rpoplpush, :rpush, :rpushx, :sadd, :sadd?, :scard,
-   :sdiff, :set, :setbit, :setex, :setnx, :setrange, :sinter, :sismember, :smembers, :sort, :spop, :srandmember, :srem, :srem?, :strlen,
+   :msetnx, :persist, :pexpire, :pexpireat, :psetex, :pttl, :rename, :renamenx, :rpop, :rpoplpush, :rpush, :rpushx, :sadd, :scard,
+   :sdiff, :set, :setbit, :setex, :setnx, :setrange, :sinter, :sismember, :smembers, :sort, :spop, :srandmember, :srem, :strlen,
    :sunion, :ttl, :type, :watch, :zadd, :zcard, :zcount, :zincrby, :zrange, :zrangebyscore, :zrank, :zrem, :zremrangebyrank,
    :zremrangebyscore, :zrevrange, :zrevrangebyscore, :zrevrank, :zrangebyscore,
    :dump, :restore].each do |m|

spec/lib/discourse_redis_spec.rb

@@ -113,26 +113,6 @@ RSpec.describe DiscourseRedis do
         expect(redis.mget('key1', 'key2')).to eq(['1', '2'])
         expect(redis.scan_each.to_a).to contain_exactly('key1', 'key2')
       end
-
-      describe '#sadd?' do
-        it "should send the right command with the right key prefix to redis" do
-          redis = DiscourseRedis.new
-
-          redis.without_namespace.expects(:sadd?).with("default:testset", "1")
-
-          redis.sadd?("testset", "1")
-        end
-      end
-
-      describe '#srem?' do
-        it "should send the right command with the right key prefix to redis" do
-          redis = DiscourseRedis.new
-
-          redis.without_namespace.expects(:srem?).with("default:testset", "1")
-
-          redis.srem?("testset", "1")
-        end
-      end
     end
 
     describe 'when namespace is disabled' do