Lower retry backoff factor for IMDS managed identity (Azure#18554)

Author: chlowell

sdk/identity/azure-identity/azure/identity/_credentials/imds.py

@@ -25,7 +25,7 @@
 
 PIPELINE_SETTINGS = {
     "connection_timeout": 2,
-    "retry_backoff_factor": 4,
+    "retry_backoff_factor": 2,
     "retry_backoff_max": 60,
     "retry_on_status_codes": [404, 429] + list(range(500, 600)),
     "retry_status": 5,