[Partition Client] Error while calling getParitionList & getPartitionInfo

While issuing request to get partition list and info, ETP server yield following error

[2022-Jul-28 17:10:04] Error: openETPServer: Error: basic_string::_M_construct null not valid

Issue appears to be a nullptr added in BaseClient::makeRequest call link.

This causes the pipeline to break in azure_deploy step