Fix get_endpoint
Fix get_endpoint

Different endpoint urls can be searched with 'admin', 'internal' and
'public' interface.

Change-Id: I57207826d0dc2c18ce0e6a0abf09140f639f64ba
Signed-off-by: Linda Wang <81613bebe84fa394bbc7c5cc1c21989c9bff2c52@huawei.com>

mywulin/functest,mywulin/functest,opnfv/functest,opnfv/functest