Allow data stream overrides for integration packages during system tests.

[ShourieG]

Some integrations like amazon security lake use routing rules to route results to a different data stream from a central data stream. Having such a mechanism the standard system tests fail since it always searches for hits in the central data stream which is generally where the system tests reside. We need a way to dynamically instruct elastic-package to look for hits in a specific data stream during system tests and also validated the results against the overridden data stream allowing the tests to pass.

This issue supersedes the issue: #1917, and takes into consideration the suggestions specified there.