xds: log bootstrap config missing warning from env var only when debugging (#8039)

Author: purnesh42H

xds/internal/xdsclient/clientimpl.go

@@ -101,7 +101,9 @@ func init() {
 	// attempting to create an xDS client, else xDS client creation will fail.
 	config, err := bootstrap.GetConfiguration()
 	if err != nil {
-		logger.Warningf("Failed to read xDS bootstrap config from env vars:  %v", err)
+		if logger.V(2) {
+			logger.Infof("Failed to read xDS bootstrap config from env vars:  %v", err)
+		}
 		DefaultPool = &Pool{clients: make(map[string]*clientRefCounted)}
 		return
 	}