Remove deprecated /api/v1/usage/attribution (#1571)

Co-authored-by: ci.datadog-api-spec <packages@datadoghq.com>
Co-authored-by: api-clients-generation-pipeline[bot] <54105614+api-clients-generation-pipeline[bot]@users.noreply.github.com>

Author: api-clients-generation-pipeline[bot]

.apigentools-info

@@ -4,13 +4,13 @@
     "spec_versions": {
         "v1": {
             "apigentools_version": "1.6.6",
-            "regenerated": "2024-03-22 16:45:29.422081",
-            "spec_repo_commit": "733f0b89"
+            "regenerated": "2024-03-22 19:28:34.416292",
+            "spec_repo_commit": "b8f385dc"
         },
         "v2": {
             "apigentools_version": "1.6.6",
-            "regenerated": "2024-03-22 16:45:29.439834",
-            "spec_repo_commit": "733f0b89"
+            "regenerated": "2024-03-22 19:28:34.433708",
+            "spec_repo_commit": "b8f385dc"
         }
     }
 }