Remove dependency list usage data from Redis

This removes any existing counters for the dependency list usage data
from Redis. Freeing up the memory it was taking.

Changelog: other
EE: true

db/post_migrate/20220310141349_remove_dependency_list_usage_data_from_redis.rb

+# frozen_string_literal: true
+
+class RemoveDependencyListUsageDataFromRedis < Gitlab::Database::Migration[1.0]
+  disable_ddl_transaction!
+
+  def up
+    Gitlab::Redis::SharedState.with { |r| r.del("DEPENDENCY_LIST_USAGE_COUNTER") }
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20220310141349

+39785d4140c7345ddbe62417576381654ce22d505ee5c92a84425f0a3f8e4935
\ No newline at end of file

spec/migrations/20220310141349_remove_dependency_list_usage_data_from_redis_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+require_migration!
+
+RSpec.describe RemoveDependencyListUsageDataFromRedis, :migration, :clean_gitlab_redis_shared_state do
+  let(:key) { "DEPENDENCY_LIST_USAGE_COUNTER" }
+
+  describe "#up" do
+    it 'removes the hash from redis' do
+      with_redis do |redis|
+        redis.hincrby(key, 1, 1)
+        redis.hincrby(key, 2, 1)
+      end
+
+      expect { migrate! }.to change { with_redis { |r| r.hgetall(key) } }.from({ '1' => '1', '2' => '1' }).to({})
+    end
+  end
+
+  def with_redis(&block)
+    Gitlab::Redis::SharedState.with(&block)
+  end
+end