Fix update project statistic specs

These specs require an already persisted project for the statistics
to be reloaded or updated

spec/models/ci/job_artifact_spec.rb

@@ -20,7 +20,9 @@ RSpec.describe Ci::JobArtifact do
   it_behaves_like 'having unique enum values'
 
   it_behaves_like 'UpdateProjectStatistics' do
-    subject { build(:ci_job_artifact, :archive, size: 107464) }
+    let_it_be(:job, reload: true) { create(:ci_build) }
+
+    subject { build(:ci_job_artifact, :archive, job: job, size: 107464) }
   end
 
   describe '.not_expired' do

spec/models/ci/pipeline_artifact_spec.rb

@@ -13,7 +13,9 @@ RSpec.describe Ci::PipelineArtifact, type: :model do
   it_behaves_like 'having unique enum values'
 
   it_behaves_like 'UpdateProjectStatistics' do
-    subject { build(:ci_pipeline_artifact) }
+    let_it_be(:pipeline, reload: true) { create(:ci_pipeline) }
+
+    subject { build(:ci_pipeline_artifact, pipeline: pipeline) }
   end
 
   describe 'validations' do

spec/models/packages/package_file_spec.rb

@@ -33,15 +33,17 @@ RSpec.describe Packages::PackageFile, type: :model do
   end
 
   context 'updating project statistics' do
+    let_it_be(:package, reload: true) { create(:package) }
+
     context 'when the package file has an explicit size' do
       it_behaves_like 'UpdateProjectStatistics' do
-        subject { build(:package_file, :jar, size: 42) }
+        subject { build(:package_file, :jar, package: package, size: 42) }
       end
     end
 
     context 'when the package file does not have a size' do
       it_behaves_like 'UpdateProjectStatistics' do
-        subject { build(:package_file, size: nil) }
+        subject { build(:package_file, package: package, size: nil) }
       end
     end
   end