Resolve dependency on global state in rubyserver.SetHeaders

SetHeaders function relies on the GetObjectDirectoryPath helper. Internally it access global variable config.Config. This dependency cause us a lot of issues in testing. To address this issue the code was moved into Locator abstraction that is now could be injected in proper places. As old function GetObjectDirectoryPath removed all places of its invocation changed to use Locator.GetObjectDirectoryPath. The func SetHeadersWithoutRepoCheck removed as it not used in prod code.

Part of: #2699 (closed)