DEV: Call Discourse.redis.flushdb after the end of each test (#29117)

There have been too many flaky tests as a result of leaking state in
Redis so it is easier to resolve them by ensuring we flush Redis'
database.

Locally on my machine, calling `Discourse.redis.flushdb` takes around
0.1ms which means this change will have very little impact on test
runtimes.

spec/lib/auth/default_current_user_provider_spec.rb

@@ -199,8 +199,6 @@ RSpec.describe Auth::DefaultCurrentUserProvider do
     context "with rate limiting" do
       before { RateLimiter.enable }
 
-      use_redis_snapshotting
-
       it "rate limits admin api requests" do
         global_setting :max_admin_api_reqs_per_minute, 3
 

spec/lib/middleware/anonymous_cache_spec.rb

@@ -230,8 +230,6 @@ RSpec.describe Middleware::AnonymousCache do
   describe "#force_anonymous!" do
     before { RateLimiter.enable }
 
-    use_redis_snapshotting
-
     it "will revert to anonymous once we reach the limit" do
       is_anon = false
 

spec/lib/middleware/request_tracker_spec.rb

@@ -258,8 +258,6 @@ RSpec.describe Middleware::RequestTracker do
         )
       end
 
-      use_redis_snapshotting
-
       def log_topic_view(authenticated: false, deferred: false)
         headers = { "action_dispatch.remote_ip" => "127.0.0.1" }
 
@@ -519,8 +517,6 @@ RSpec.describe Middleware::RequestTracker do
       freeze_time_safe
     end
 
-    use_redis_snapshotting
-
     after { Rails.logger = @orig_logger }
 
     let :middleware do

spec/lib/mini_scheduler_long_running_job_logger_spec.rb

@@ -3,8 +3,6 @@
 require "mini_scheduler_long_running_job_logger"
 
 RSpec.describe MiniSchedulerLongRunningJobLogger do
-  use_redis_snapshotting
-
   class Every10MinutesJob
     extend ::MiniScheduler::Schedule
 

spec/lib/post_action_creator_spec.rb

@@ -9,8 +9,6 @@ RSpec.describe PostActionCreator do
   describe "rate limits" do
     before { RateLimiter.enable }
 
-    use_redis_snapshotting
-
     it "limits redo/undo" do
       PostActionCreator.like(user, post)
       PostActionDestroyer.destroy(user, post, :like)

spec/lib/post_revisor_spec.rb

@@ -306,10 +306,6 @@ RSpec.describe PostRevisor do
   end
 
   describe "revise wiki" do
-    # There used to be a bug where wiki changes were considered posting "too similar"
-    # so this is enabled and checked
-    use_redis_snapshotting
-
     before { SiteSetting.unique_posts_mins = 10 }
 
     it "allows the user to change it to a wiki" do
@@ -803,8 +799,6 @@ RSpec.describe PostRevisor do
         SiteSetting.editing_grace_period = 0
       end
 
-      use_redis_snapshotting
-
       it "triggers a rate limiter" do
         EditRateLimiter.any_instance.expects(:performed!)
         post_revisor.revise!(changed_by, raw: "updated body")

spec/lib/site_settings/deprecated_settings_spec.rb

@@ -34,10 +34,6 @@ RSpec.xdescribe SiteSettings::DeprecatedSettings do
   describe "when not overriding deprecated settings" do
     let(:override) { false }
 
-    # Necessary because Discourse.deprecate uses redis to see if the warning
-    # was already logged.
-    use_redis_snapshotting
-
     # NOTE: This fixture has some completely made up settings (e.g. min_trust_level_to_allow_invite_tl_and_staff)
     let(:deprecated_test) { "#{Rails.root}/spec/fixtures/site_settings/deprecated_test.yml" }
 

spec/lib/topic_query_spec.rb

@@ -1489,8 +1489,6 @@ RSpec.describe TopicQuery do
   end
 
   describe "#list_suggested_for" do
-    use_redis_snapshotting
-
     def clear_cache!
       Discourse.redis.keys("random_topic_cache*").each { |k| Discourse.redis.del k }
     end