chore: fix setup_telemetry script (#3680)

# What does this PR do?
Added missing configuration files

## Test Plan
run ./scripts/telemetry/setup_telemetry.sh
```
OTEL_SERVICE_NAME=llama_stack OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 TELEMETRY_SINKS=otel_trace,otel_metric uv run --with llama-stack llama stack build --distro=starter --image-type=venv --run
```
Navigate to grafana localhost:3000, query metrics and traces

scripts/telemetry/grafana-datasources.yaml

@@ -0,0 +1,15 @@
+apiVersion: 1
+
+datasources:
+  - name: Prometheus
+    type: prometheus
+    access: proxy
+    url: http://prometheus:9090
+    isDefault: true
+    editable: true
+
+  - name: Jaeger
+    type: jaeger
+    access: proxy
+    url: http://jaeger:16686
+    editable: true