Get rid of more requires, which causes warnings when code is reloaded

Signed-off-by: Rémy Coutable <remy@rymai.me>

app/models/commit.rb

@@ -12,11 +12,11 @@ class Commit
   attr_accessor :project
-  DIFF_SAFE_LINES ||= Gitlab::Git::DiffCollection::DEFAULT_LIMITS[:max_lines]
+  DIFF_SAFE_LINES = Gitlab::Git::DiffCollection::DEFAULT_LIMITS[:max_lines]
   # Commits above this size will not be rendered in HTML
-  DIFF_HARD_LIMIT_FILES ||= 1000
-  DIFF_HARD_LIMIT_LINES ||= 50000
+  DIFF_HARD_LIMIT_FILES = 1000
+  DIFF_HARD_LIMIT_LINES = 50000
   class << self
     def decorate(commits, project)

app/models/merge_request.rb

@@ -27,9 +27,6 @@
 #  merge_commit_sha          :string
 #
-require Rails.root.join("app/models/commit")
-require Rails.root.join("lib/static_model")
-
 class MergeRequest < ActiveRecord::Base
   include InternalId
   include Issuable

app/models/merge_request_diff.rb

@@ -11,8 +11,6 @@
 #  updated_at       :datetime
 #
-require Rails.root.join("app/models/commit")
-
 class MergeRequestDiff < ActiveRecord::Base
   include Sortable

lib/file_size_validator.rb

 class FileSizeValidator < ActiveModel::EachValidator
-  MESSAGES ||= { is: :wrong_size, minimum: :size_too_small, maximum: :size_too_big }.freeze
-  CHECKS   ||= { is: :==, minimum: :>=, maximum: :<= }.freeze
-  DEFAULT_TOKENIZER ||= -> (value) { value.split(//) }.freeze
-  RESERVED_OPTIONS  ||= [:minimum, :maximum, :within, :is, :tokenizer, :too_short, :too_long].freeze
+  MESSAGES = { is: :wrong_size, minimum: :size_too_small, maximum: :size_too_big }.freeze
+  CHECKS   = { is: :==, minimum: :>=, maximum: :<= }.freeze
+  DEFAULT_TOKENIZER = -> (value) { value.split(//) }.freeze
+  RESERVED_OPTIONS  = [:minimum, :maximum, :within, :is, :tokenizer, :too_short, :too_long].freeze
   def initialize(options)
     if range = (options.delete(:in) || options.delete(:within))