Improve specs for pipeline and pipeline seeds

spec/lib/gitlab/ci/stage/seed_spec.rb

@@ -30,7 +30,7 @@ describe Gitlab::Ci::Stage::Seed do
   end
 
   describe '#user=' do
-    let(:user) { create(:user) }
+    let(:user) { build(:user) }
 
     it 'assignes relevant pipeline attributes' do
       subject.user = user

spec/models/ci/pipeline_spec.rb

@@ -535,9 +535,9 @@ describe Ci::Pipeline, models: true do
     end
   end
 
-  describe '#has_stage_seedss?' do
+  describe '#has_stage_seeds?' do
     context 'when pipeline has stage seeds' do
-      subject { create(:ci_pipeline_with_one_job) }
+      subject { build(:ci_pipeline_with_one_job) }
 
       it { is_expected.to have_stage_seeds }
     end