Quarantine flaky DST specs

ee/spec/finders/incident_management/oncall_users_finder_spec.rb

@@ -108,7 +108,7 @@ RSpec.describe IncidentManagement::OncallUsersFinder do
           end
         end
 
-        context 'with no persisted shifts for oncall_at time' do
+        context 'with no persisted shifts for oncall_at time', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/343506' do
           let(:oncall_at) { after_second_shift }
 
           it { is_expected.to contain_exactly(user_1, user_2, user_4) }

ee/spec/services/incident_management/oncall_rotations/remove_participant_service_spec.rb

@@ -42,7 +42,7 @@ RSpec.describe IncidentManagement::OncallRotations::RemoveParticipantService do
     # Create an historial shift (other participant)
     let!(:historical_shift) { create(:incident_management_oncall_shift, rotation: rotation, participant: other_participant, starts_at: rotation.starts_at, ends_at: ends_at(rotation.starts_at)) }
 
-    context 'with historial and current shift' do
+    context 'with historial and current shift', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/343506' do
       # Create a current shift (particpant being removed)
       let!(:current_shift) { create(:incident_management_oncall_shift, rotation: rotation, participant: participant, starts_at: historical_shift.ends_at, ends_at: ends_at(historical_shift.ends_at)) }
 
@@ -63,7 +63,7 @@ RSpec.describe IncidentManagement::OncallRotations::RemoveParticipantService do
       end
     end
 
-    context 'when current shift has not been created' do
+    context 'when current shift has not been created', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/343506' do
       it 'creates the current shift and cuts it short' do
         expect { execute }.to change { rotation.shifts.count }.from(1).to(3)