[Identity] node-fetch takes above 2 seconds to send the request on some environments (Azure#15937)

Author: sadasant

sdk/identity/identity/src/credentials/managedIdentityCredential/imdsMsi.ts

@@ -90,7 +90,11 @@ export const imdsMsi: MSI = {
       // not having a "Metadata" header should cause an error to be
       // returned quickly from the endpoint, proving its availability.
       const webResource = identityClient.createWebResource(request);
-      webResource.timeout = updatedOptions?.requestOptions?.timeout || 500;
+
+      // In Kubernetes pods, node-fetch (used by core-http) takes longer than 2 seconds to begin sending the network request,
+      // So smaller timeouts will cause this credential to be immediately aborted.
+      // This won't be a problem once we move Identity to core-rest-pipeline.
+      webResource.timeout = updatedOptions?.requestOptions?.timeout || 3000;
 
       try {
         logger.info(`Pinging IMDS endpoint`);