Raisl5: Fix Gitlab::Database::LoadBalancing#caught_up? check

Rails 5 returns true/false instead of a string 't' or 'f'.

ee/changelogs/unreleased/8583-rails5-gitlab-database-loadbalancing-caught_up-returns-state-incorrectly.yml

+---
+title: 'Raisl 5: Fix Gitlab::Database::LoadBalancing#caught_up? check'
+merge_request: 8595
+author:
+type: fixed

ee/lib/gitlab/database/load_balancing/host.rb

@@ -159,7 +159,7 @@ module Gitlab
 
           row = query_and_release(query)
 
-          row['result'] == 't'
+          ::Gitlab::Utils.to_boolean(row['result'])
         rescue *CONNECTION_ERRORS
           false
         end

ee/spec/lib/gitlab/database/load_balancing/host_spec.rb

@@ -323,6 +323,14 @@ describe Gitlab::Database::LoadBalancing::Host, :postgresql do
       expect(host.caught_up?('foo')).to eq(true)
     end
 
+    # TODO: remove rails5-only tag after removing rails4 tests
+    it 'returns true when a host has caught up', :rails5 do
+      allow(host).to receive(:connection).and_return(connection)
+      expect(connection).to receive(:select_all).and_return([{ 'result' => true }])
+
+      expect(host.caught_up?('foo')).to eq(true)
+    end
+
     it 'returns false when a host has not caught up' do
       allow(host).to receive(:connection).and_return(connection)
       expect(connection).to receive(:select_all).and_return([{ 'result' => 'f' }])
@@ -330,6 +338,14 @@ describe Gitlab::Database::LoadBalancing::Host, :postgresql do
       expect(host.caught_up?('foo')).to eq(false)
     end
 
+    # TODO: remove rails5-only tag after removing rails4 tests
+    it 'returns false when a host has not caught up', :rails5 do
+      allow(host).to receive(:connection).and_return(connection)
+      expect(connection).to receive(:select_all).and_return([{ 'result' => false }])
+
+      expect(host.caught_up?('foo')).to eq(false)
+    end
+
     it 'returns false when the connection fails' do
       wrapped_error = wrapped_exception(ActionView::Template::Error, StandardError)