fix: use same metric description as OTel (#22192) (#22293)

Signed-off-by: Erhhung Yuan <erhhung@gmail.com>

backend/open_webui/utils/telemetry/metrics.py

@@ -120,12 +120,12 @@ def setup_metrics(app: FastAPI, resource: Resource) -> None:
     # Instruments
     request_counter = meter.create_counter(
         name="http.server.requests",
-        description="Total HTTP requests",
+        description="Counts the total number of inbound HTTP requests.",
         unit="1",
     )
     duration_histogram = meter.create_histogram(
         name="http.server.duration",
-        description="HTTP request duration",
+        description="Measures the duration of inbound HTTP requests.",
         unit="ms",
     )