Fix for on-call escalation policies endpoint

[api-clients-generation-pipeline]

See DataDog/datadog-api-spec#3774
Test branch datadog-api-spec/test/d.marin/oncall_ep

[datadog-datadog-prod-us1]

Datadog Report

Branch report: datadog-api-spec/generated/3774
Commit report: 27fd308
Test service: datadog-api-client-ruby

❌ 6 Failed (0 Known Flaky), 46 Passed, 2108 Skipped, 58.94s Total duration (1m 11.77s time saved)

❌ Failed Tests (6)

This report shows up to 5 failed tests.

• Create on-call escalation policy returns "Created" response - On-Call at features/v2/on-call.feature

• Create on-call escalation policy returns "Created" response - On-Call at features/v2/on-call.feature

• Delete on-call escalation policy returns "No Content" response - On-Call at features/v2/on-call.feature

• Delete on-call escalation policy returns "No Content" response - On-Call at features/v2/on-call.feature - Details

  Expand for error

   There are unused HTTP interactions left in the cassette:
     - [post https://api.datadoghq.com/api/v2/on-call/escalation-policies] => [201 "{\"data\":{\"id\":\"5c8e2b45-17f7-47e7-b489-c97fa1f98fae\",\"type\":\"policies\",\"attribut"]
     - [delete https://api.datadoghq.com/api/v2/on-call/escalation-policies/5c8e2b45-17f7-47e7-b489-c97fa1f98fae] => [204 ""]
     - [delete https://api.datadoghq.com/api/v2/on-call/escalation-policies/5c8e2b45-17f7-47e7-b489-c97fa1f98fae] => [404 "{\"errors\":[{\"title\":\"Generic Error\",\"detail\":\"escalation_policy[5c8e2b45-17f7-47"]
  

• Update on-call escalation policy returns "OK" response - On-Call at features/v2/on-call.feature