DEV: Remove logical OR assignment of constants (#29201)

Constants should always be only assigned once. The logical OR assignment
of a constant is a relic of the past before we used zeitwerk for
autoloading and had bugs where a file could be loaded twice resulting in
constant redefinition warnings.

db/post_migrate/20240202052058_drop_badge_image_column.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DropBadgeImageColumn < ActiveRecord::Migration[7.0]
-  DROPPED_COLUMNS ||= { badges: %i[image] }
+  DROPPED_COLUMNS = { badges: %i[image] }
 
   def up
     DROPPED_COLUMNS.each { |table, columns| Migration::ColumnDropper.execute_drop(table, columns) }

db/post_migrate/20240212034010_drop_deprecated_columns.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DropDeprecatedColumns < ActiveRecord::Migration[7.0]
-  DROPPED_COLUMNS ||= {
+  DROPPED_COLUMNS = {
     categories: %i[suppress_from_latest required_tag_group_id min_tags_from_required_group],
     directory_columns: %i[automatic],
     email_tokens: %i[token],

db/post_migrate/20240612073116_swap_field_type_with_field_type_enum_on_user_fields.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class SwapFieldTypeWithFieldTypeEnumOnUserFields < ActiveRecord::Migration[7.0]
-  # DROPPED_COLUMNS ||= { user_fields: %i[field_type] }
+  # DROPPED_COLUMNS = { user_fields: %i[field_type] }
 
   # def up
   #   # WARNING: Swapping in a column of a different type in a post-migration will break the AR

db/post_migrate/20240711123755_drop_compiled_js_from_translation_overrides.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DropCompiledJsFromTranslationOverrides < ActiveRecord::Migration[7.1]
-  DROPPED_COLUMNS ||= { translation_overrides: %i[compiled_js] }
+  DROPPED_COLUMNS = { translation_overrides: %i[compiled_js] }
 
   def up
     DROPPED_COLUMNS.each { |table, columns| Migration::ColumnDropper.execute_drop(table, columns) }

db/post_migrate/20240714231516_drop_custom_type_from_flags.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DropCustomTypeFromFlags < ActiveRecord::Migration[7.0]
-  DROPPED_COLUMNS ||= { flags: %i[custom_type] }
+  DROPPED_COLUMNS = { flags: %i[custom_type] }
 
   def up
     DROPPED_COLUMNS.each { |table, columns| Migration::ColumnDropper.execute_drop(table, columns) }

db/post_migrate/20240717053710_drop_groups_smtp_ssl.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DropGroupsSmtpSsl < ActiveRecord::Migration[7.1]
-  DROPPED_COLUMNS ||= { groups: %i[smtp_ssl] }
+  DROPPED_COLUMNS = { groups: %i[smtp_ssl] }
 
   def up
     DROPPED_COLUMNS.each { |table, columns| Migration::ColumnDropper.execute_drop(table, columns) }