Remove CarrierWave initializer

This is stale and no longer used. Object storage is now configured
in each specific gitlab.yml section (e.g. uploads, lfs, etc.).

Part of gitlab-org/omnibus-gitlab#3641

config/aws.yml.example

-# See https://github.com/jnicklas/carrierwave#using-amazon-s3
-# for more options
-# If you change this file in a Merge Request, please also create
-# a Merge Request on https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests
-#
-production:
-  access_key_id: AKIA1111111111111UA
-  secret_access_key: secret
-  bucket: mygitlab.production.us
-  region: us-east-1
-
-development:
-  access_key_id: AKIA1111111111111UA
-  secret_access_key: secret
-  bucket: mygitlab.development.us
-  region: us-east-1
-
-test:
-  access_key_id: AKIA1111111111111UA
-  secret_access_key: secret
-  bucket: mygitlab.test.us
-  region: us-east-1

config/initializers/carrierwave.rb

-CarrierWave::SanitizedFile.sanitize_regexp = /[^[:word:]\.\-\+]/
-
-aws_file = Rails.root.join('config', 'aws.yml')
-
-if File.exist?(aws_file)
-  AWS_CONFIG = YAML.load(File.read(aws_file))[Rails.env]
-
-  CarrierWave.configure do |config|
-    config.fog_provider = 'fog/aws'
-
-    config.fog_credentials = {
-      provider: 'AWS',                                        # required
-      aws_access_key_id: AWS_CONFIG['access_key_id'],         # required
-      aws_secret_access_key: AWS_CONFIG['secret_access_key'], # required
-      region: AWS_CONFIG['region'],                           # optional, defaults to 'us-east-1'
-    }
-
-    # required
-    config.fog_directory = AWS_CONFIG['bucket']
-
-    # optional, defaults to true
-    config.fog_public = false
-
-    # optional, defaults to {}
-    config.fog_attributes = { 'Cache-Control' => 'max-age=315576000' }
-
-    # optional time (in seconds) that authenticated urls will be valid.
-    # when fog_public is false and provider is AWS or Google, defaults to 600
-    config.fog_authenticated_url_expiration = 1 << 29
-  end
-end