Remove parallel since it's unused

Gemfile

@@ -8,7 +8,6 @@ gem 'jbuilder', '~> 2.10'
 gem 'bootsnap', '~> 1.4', require: false # Large rails application booting enhancer
 gem 'font_assets', '~> 0.1.14' # for serving fonts on cdn https://github.com/ericallam/font_assets
 gem 'hamster', '~> 3.0' # Thread-safe collection classes for Ruby
-gem 'parallel', '~> 1.17' # run processes in parallel
 gem 'puma_worker_killer', '~> 0.1.1' # TODO: Investigate why puma workers need to be killed.
 gem 'puma', '~> 4.0', '>= 4.0.1'
 gem 'rake', '~> 12.3.2'

Gemfile.lock

@@ -98,7 +98,6 @@ GEM
       zeitwerk (~> 2.2, >= 2.2.2)
     addressable (2.6.0)
       public_suffix (>= 2.0.2, < 4.0)
-    amq-protocol (2.3.0)
     andand (1.3.3)
     ast (2.4.0)
     babel-source (5.8.35)
@@ -109,8 +108,6 @@ GEM
     bootsnap (1.4.4)
       msgpack (~> 1.0)
     builder (3.2.4)
-    bunny (2.14.2)
-      amq-protocol (~> 2.3, >= 2.3.0)
     byebug (11.0.1)
     chronic (0.10.2)
     coderay (1.1.2)
@@ -419,7 +416,6 @@ DEPENDENCIES
   action_mailer_matchers (~> 1.2)
   bess!
   bootsnap (~> 1.4)
-  bunny (~> 2.14, >= 2.14.2)
   byebug (~> 11.0, >= 11.0.1)
   chronic (~> 0.10.2)
   colorize (~> 0.8.1)
@@ -446,7 +442,6 @@ DEPENDENCIES
   mail_view (~> 2.0)
   money (~> 6.13)
   nearest_time_zone (~> 0.0.4)
-  parallel (~> 1.17)
   parallel_tests (~> 2.32)
   param_validation!
   pg (~> 0.11)

lib/parallel_ar.rb

@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-
-# License: AGPL-3.0-or-later WITH WTO-AP-3.0-or-later
-# Full license explanation at https://github.com/houdiniproject/houdini/blob/master/LICENSE
-require 'parallel'
-
-module ParallelAr
-  def self.reduce(arr, accum, &block)
-    Parallel.each(arr, in_threads: 8) do |elem|
-      ActiveRecord::Base.connection_pool.with_connection do
-        ActiveRecord::Base.transaction do
-          accum = block.call(accum, elem)
-        end
-      end
-    end
-    accum
-  end
-end