ref(alerts): Increase Seer timeout (#77038)

When Seer is deployed it takes longer to respond as it's doing some
compilation but this result in users not being able to create or edit
their dynamic rules, so we'll give it more time.

src/sentry/conf/server.py

@@ -3153,7 +3153,7 @@ def custom_parameter_sort(parameter: dict) -> tuple[str, int]:
 
 SEER_ANOMALY_DETECTION_MODEL_VERSION = "v1"
 SEER_ANOMALY_DETECTION_URL = SEER_DEFAULT_URL  # for local development, these share a URL
-SEER_ANOMALY_DETECTION_TIMEOUT = 5
+SEER_ANOMALY_DETECTION_TIMEOUT = 15
 
 SEER_ANOMALY_DETECTION_ENDPOINT_URL = (
     f"/{SEER_ANOMALY_DETECTION_MODEL_VERSION}/anomaly-detection/detect"