Remove report_on_long_redis_durations flag

This was used for a GitLab-internal investigation, and we believe we
have identified the cause as RDB backups:
https://gitlab.com/groups/gitlab-com/gl-infra/-/epics/566

Changelog: other

config/feature_flags/development/report_on_long_redis_durations.yml

----
-name: report_on_long_redis_durations
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/67512
-rollout_issue_url: https://gitlab.com/gitlab-com/gl-infra/scalability/-/issues/1183
-milestone: '14.2'
-type: development
-group: team::Scalability
-default_enabled: false

lib/gitlab/instrumentation/redis_interceptor.rb

@@ -5,10 +5,6 @@ module Gitlab
     module RedisInterceptor
       APDEX_EXCLUDE = %w[brpop blpop brpoplpush bzpopmin bzpopmax xread xreadgroup].freeze
 
-      # These are temporary to help with investigating
-      # https://gitlab.com/gitlab-com/gl-infra/scalability/-/issues/1183
-      DURATION_ERROR_THRESHOLD = 1.25.seconds
-
       class MysteryRedisDurationError < StandardError
         attr_reader :backtrace
 
@@ -19,7 +15,6 @@ module Gitlab
 
       def call(*args, &block)
         start = Gitlab::Metrics::System.monotonic_time # must come first so that 'start' is always defined
-        start_real_time = Time.now
         instrumentation_class.instance_count_request
         instrumentation_class.redis_cluster_validate!(args.first)
 
@@ -40,16 +35,6 @@ module Gitlab
           instrumentation_class.add_duration(duration)
           instrumentation_class.add_call_details(duration, args)
         end
-
-        if duration > DURATION_ERROR_THRESHOLD &&
-           instrumentation_class == ::Gitlab::Instrumentation::Redis::SharedState &&
-           Feature.enabled?(:report_on_long_redis_durations, default_enabled: :yaml)
-
-          Gitlab::ErrorTracking.track_exception(MysteryRedisDurationError.new(caller),
-                                                command: command_from_args(args),
-                                                duration: duration,
-                                                timestamp: start_real_time.iso8601(5))
-        end
       end
 
       def write(command)

spec/lib/gitlab/instrumentation/redis_interceptor_spec.rb

@@ -111,45 +111,4 @@ RSpec.describe Gitlab::Instrumentation::RedisInterceptor, :clean_gitlab_redis_sh
       end
     end
   end
-
-  context 'when a command takes longer than DURATION_ERROR_THRESHOLD' do
-    let(:threshold) { 0.5 }
-
-    before do
-      stub_const("#{described_class}::DURATION_ERROR_THRESHOLD", threshold)
-    end
-
-    context 'when report_on_long_redis_durations is disabled' do
-      it 'does nothing' do
-        stub_feature_flags(report_on_long_redis_durations: false)
-
-        expect(Gitlab::ErrorTracking).not_to receive(:track_exception)
-
-        Gitlab::Redis::SharedState.with { |r| r.mget('foo', 'foo') { sleep threshold + 0.1 } }
-      end
-    end
-
-    context 'when report_on_long_redis_durations is enabled' do
-      context 'for an instance other than SharedState' do
-        it 'does nothing' do
-          expect(Gitlab::ErrorTracking).not_to receive(:track_exception)
-
-          Gitlab::Redis::Queues.with { |r| r.mget('foo', 'foo') { sleep threshold + 0.1 } }
-        end
-      end
-
-      context 'for the SharedState instance' do
-        it 'tracks an exception and continues' do
-          expect(Gitlab::ErrorTracking)
-            .to receive(:track_exception)
-                  .with(an_instance_of(described_class::MysteryRedisDurationError),
-                        command: 'mget',
-                        duration: be > threshold,
-                        timestamp: a_string_matching(/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{5}/))
-
-          Gitlab::Redis::SharedState.with { |r| r.mget('foo', 'foo') { sleep threshold + 0.1 } }
-        end
-      end
-    end
-  end
 end