Update http_flask.py (Azure#31951)

Author: tonybaloney

sdk/monitor/azure-monitor-opentelemetry/samples/tracing/http_flask.py

@@ -3,12 +3,14 @@
 # Licensed under the MIT License. See License in the project root for
 # license information.
 # --------------------------------------------------------------------------
-import flask
 from azure.monitor.opentelemetry import configure_azure_monitor
 
 # Configure Azure monitor collection telemetry pipeline
 configure_azure_monitor()
 
+# Import Flask after running configure_azure_monitor()
+import flask
+
 app = flask.Flask(__name__)