remove the value of login info in log-manager (#108)

Co-authored-by: Rui Gao <ruigao@microsoft.com>

Author: hippogr

src/log-manager/config/log-manager.yaml

@@ -18,7 +18,7 @@
 service_type: "k8s"
 
 port: 9103
-admin_name: "admin"
-admin_password: "admin"
+admin_name: ""
+admin_password: ""
 jwt_secret: "jwt_secret"
 token_expired_second: 120