Prevent daylight-savings-related failures in oncall specs

ee/spec/graphql/resolvers/incident_management/oncall_shifts_resolver_spec.rb

@@ -6,7 +6,7 @@ RSpec.describe Resolvers::IncidentManagement::OncallShiftsResolver do
   include GraphqlHelpers
 
   let_it_be(:current_user) { create(:user) }
-  let_it_be(:rotation) { create(:incident_management_oncall_rotation, :with_participant) }
+  let_it_be(:rotation) { create(:incident_management_oncall_rotation, :with_participant, :utc) }
   let_it_be(:project) { rotation.project }
   let(:args) { { start_time: rotation.starts_at, end_time: rotation.starts_at + rotation.shift_cycle_duration } }
 

ee/spec/services/incident_management/oncall_shifts/read_service_spec.rb

@@ -7,7 +7,7 @@ RSpec.describe ::IncidentManagement::OncallShifts::ReadService do
   let_it_be(:user_without_permissions) { create(:user) }
   let_it_be(:current_user) { user_with_permissions }
 
-  let_it_be_with_refind(:rotation) { create(:incident_management_oncall_rotation, length: 1, length_unit: :days) }
+  let_it_be_with_refind(:rotation) { create(:incident_management_oncall_rotation, :utc, length: 1, length_unit: :days) }
   let_it_be(:participant) { create(:incident_management_oncall_participant, :with_developer_access, rotation: rotation) }
   let_it_be(:project) { rotation.project }
 

ee/spec/workers/incident_management/oncall_rotations/persist_shifts_job_spec.rb

@@ -59,6 +59,7 @@ RSpec.describe IncidentManagement::OncallRotations::PersistShiftsJob do
             :incident_management_oncall_rotation,
             :with_active_period, # 8:00 - 17:00
             :with_participant,
+            :utc,
             created_at: created_at, # Monday @ 5:00
             starts_at: starts_at, # Tuesday @ 00:00
             updated_at: updated_at # Friday @ 6:00
@@ -174,6 +175,7 @@ RSpec.describe IncidentManagement::OncallRotations::PersistShiftsJob do
         let_it_be_with_reload(:rotation) do
           create(
             :incident_management_oncall_rotation,
+            :utc,
             :with_participant,
             :with_active_period, # 8:00-17:00
             starts_at: starts_at