Restore integration tests (#2620)

* restored test_consensus

* restored test_sync

* run integration tests only on CI

* use single test-thread for integration tests

* post-merge fix

* panic when integration test runs for too long

* add some traces to integration logs

* manual wait -> timeout

* post-merge fix

* post-merge fix

substrate/core/consensus/aura/src/lib.rs

@@ -69,9 +69,9 @@ use slots::{CheckedHeader, SlotWorker, SlotInfo, SlotCompatible, slot_now, check
 
 pub use aura_primitives::*;
 pub use consensus_common::{SyncOracle, ExtraVerification};
+pub use digest::CompatibleDigestItem;
 
 mod digest;
-use digest::CompatibleDigestItem;
 
 type AuthorityId<P> = <P as Pair>::Public;