[INLONG-5582][Manager] Fix error in client API

[haifxu]

• Fixes #5585

Motivation

1.This url does not need the leading /.

2.GET requests do not support objects as parameters.

Modifications

1.Remove /.

2.Use MAP instead of object.

Verifying this change

• [x] This change is a trivial rework/code cleanup without any test coverage.