test: Added Integration Tests for Relay Pairing and Work Processing

added integration tests to improve the reliability and correctness of the erpc-scanner module. It introduces a dedicated integration_test module that validates key interactions between relays, work generation, and scanner behavior.

The tests ensure that relay nodes correctly generate IncompleteWork entries, that the scanner processes and returns CompletedWork results accurately, and that invalid self-loop circuits are properly handled.

Signed-off-by: harshita_roonwal roonwal721972@gmail.com