Changes cause success has a non-NULL constraint

`success` column cannot be NULL, so we need to adapt the code to
define what "never" synced means.

ee/app/models/geo/file_registry.rb

@@ -5,7 +5,8 @@ class Geo::FileRegistry < Geo::BaseRegistry
 
   scope :lfs_objects, -> { where(file_type: :lfs) }
   scope :attachments, -> { where(file_type: Geo::FileService::DEFAULT_OBJECT_TYPES) }
-  scope :never, -> { where(retry_count: nil) }
+  scope :failed, -> { where(success: false).where.not(retry_count: nil) }
+  scope :never, -> { where(success: false, retry_count: nil) }
   scope :fresh, -> { order(created_at: :desc) }
 
   self.inheritance_column = 'file_type'
@@ -20,14 +21,10 @@ class Geo::FileRegistry < Geo::BaseRegistry
 
   def self.with_status(status)
     case status
-    when 'synced'
-      synced
-    when 'never'
-      never
-    when 'failed'
-      failed
+    when 'synced', 'never', 'failed'
+      self.public_send(status) # rubocop: disable GitlabSecurity/PublicSend
     else
-      self
+      all
     end
   end
 
@@ -36,10 +33,10 @@ class Geo::FileRegistry < Geo::BaseRegistry
   # It takes into account things like if a successful replication has been done
   # if there are pending actions or existing errors
   #
-  # @return [Symbol] :never, :failed:, :pending or :synced
+  # @return [Symbol] :synced, :never, or :failed
   def synchronization_state
     return :synced if success?
-    return :never if success.nil? && retry_count.nil?
+    return :never if retry_count.nil?
 
     :failed
   end

ee/spec/models/geo/file_registry_spec.rb

 require 'spec_helper'
 
 describe Geo::FileRegistry do
-  set(:failed) { create(:geo_file_registry, success: false) }
-  set(:synced) { create(:geo_file_registry, success: true) }
+  set(:failed) { create(:geo_file_registry, :failed) }
+  set(:synced) { create(:geo_file_registry) }
 
   describe '.failed' do
     it 'returns registries in the failed state' do
@@ -27,10 +27,9 @@ describe Geo::FileRegistry do
 
   describe '.never' do
     it 'returns registries that are never synced' do
-      create(:geo_file_registry, retry_count: 1, success: true)
-      create(:geo_file_registry, retry_count: 2, success: false)
+      never = create(:geo_file_registry, retry_count: nil, success: false)
 
-      expect(described_class.never).to match_ids([failed, synced])
+      expect(described_class.never).to match_ids([never])
     end
   end
 
@@ -59,7 +58,7 @@ describe Geo::FileRegistry do
     end
 
     it 'returns :never for a successful registry never synced' do
-      never = build(:geo_file_registry, success: nil)
+      never = build(:geo_file_registry, success: false, retry_count: nil)
 
       expect(never.synchronization_state).to eq(:never)
     end