Rename regex constant to VALID_DOMAIN_REGEX

Per reviewer feedback

ee/app/models/allowed_email_domain.rb

@@ -14,14 +14,14 @@ class AllowedEmailDomain < ApplicationRecord
     'icloud.com'
   ].freeze
 
-  REGEX_VALIDATOR = /\w*\./.freeze
+  VALID_DOMAIN_REGEX = /\w*\./.freeze
 
   validates :group_id, presence: true
   validates :domain, presence: true
   validate :allow_root_group_only
   validates :domain, exclusion: { in: RESERVED_DOMAINS,
     message: _('The domain you entered is not allowed.') }
-  validates :domain, format: { with: REGEX_VALIDATOR,
+  validates :domain, format: { with: VALID_DOMAIN_REGEX,
     message: _('The domain you entered is misformatted.') }
 
   belongs_to :group, class_name: 'Group', foreign_key: :group_id

ee/app/views/groups/settings/_allowed_email_domain.html.haml

@@ -7,7 +7,7 @@
     = _('Restrict membership by email domain')
   .js-allowed-email-domains{ data: { hidden_input_id: hidden_input_id,
     label_id: label_id,
-    regex_validator: AllowedEmailDomain::REGEX_VALIDATOR.source,
+    regex_validator: AllowedEmailDomain::VALID_DOMAIN_REGEX.source,
     disallowed_values: AllowedEmailDomain::RESERVED_DOMAINS.to_json,
     error_message: _('The domain you entered is misformatted.'),
     disallowed_value_error_message: _('The domain you entered is not allowed.') } }