feat(billing): add transaction retention to config as span (#102095)

Author: vbro

src/sentry/quotas/base.py

@@ -71,7 +71,11 @@ def to_object(self) -> Mapping[str, Any]:
 
 # This mirrors the Retentions struct in relay
 # https://github.com/getsentry/relay/blob/641e7f20cd/relay-dynamic-config/src/project.rs#L34-L45
-RETENTIONS_CONFIG_MAPPING = {DataCategory.SPAN: "span", DataCategory.LOG_BYTE: "log"}
+RETENTIONS_CONFIG_MAPPING = {
+    DataCategory.LOG_BYTE: "log",
+    DataCategory.TRANSACTION: "span",
+    DataCategory.SPAN: "span",
+}
 
 
 def build_metric_abuse_quotas() -> list[AbuseQuota]:

tests/sentry/api/endpoints/test_relay_projectconfigs.py

@@ -192,6 +192,31 @@ def test_parse_retentions(call_endpoint, default_project):
         }
 
 
+@django_db_all
+def test_parse_retentions_with_transactions(call_endpoint, default_project):
+    with patch("sentry.quotas.backend") as quotas_mock:
+        quotas_mock.get_retentions = lambda x: {
+            DataCategory.ERROR: RetentionSettings(standard=10, downsampled=20),
+            DataCategory.REPLAY: RetentionSettings(standard=11, downsampled=21),
+            DataCategory.TRANSACTION: RetentionSettings(standard=12, downsampled=22),
+            DataCategory.LOG_BYTE: RetentionSettings(standard=13, downsampled=23),
+        }
+        quotas_mock.get_event_retention = lambda x: 45
+        quotas_mock.get_downsampled_event_retention = lambda x: 90
+
+        result, status_code = call_endpoint()
+        assert status_code < 400
+        assert_no_snakecase_key(result)
+        cfg = safe.get_path(result, "configs", str(default_project.id))
+
+        assert safe.get_path(cfg, "config", "eventRetention") == 45
+        assert safe.get_path(cfg, "config", "downsampledEventRetention") == 90
+        assert safe.get_path(cfg, "config", "retentions") == {
+            "span": {"standard": 12, "downsampled": 22},
+            "log": {"standard": 13, "downsampled": 23},
+        }
+
+
 @django_db_all
 def test_relays_dyamic_sampling(call_endpoint, default_project) -> None:
     """