BACKLOG-606 - Kettle remote execution: all requests are sent twice because authentication header is missing at 1st attempt

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BACKLOG-606 - CLONE - Kettle remote execution: all requests are sent twice because authentication header is missing at 1st attempt

Fixed "addCredentials" method, add Preemptive Authentication.
Delete AuthScope.ANY because setting credentials with AuthScope.ANY authentication scope (null value for host and/or realm) is highly discouraged in production applications.
BACKLOG-606 - Add unit test for addCredentials method
Merge pull request #731 from annapopova1/BACKLOG-606

Backlog 606