[core-edge] Do not delete store on startup.

Previously we deleted and rebuilt the whole store from the raft log
on every startup. This commit adds raft index into the transaction
log, so that we can safely recover and deduce exactly which committed
transactions from the raft log need to be appended to the transaction
log.

community/kernel/src/main/java/org/neo4j/kernel/impl/transaction/log/entry/LogEntryStart.java

@@ -130,6 +130,7 @@ public String toString( TimeZone timeZone )
                 "time=" + timestamp( timeWritten, timeZone ) + "," +
                 "lastCommittedTxWhenTransactionStarted=" + lastCommittedTxWhenTransactionStarted + "," +
                 "additionalHeaderLength=" + (additionalHeader == null ? -1 : additionalHeader.length) + "," +
+                (additionalHeader == null ? "" : Arrays.toString( additionalHeader ) ) + "," +
                 "position=" + startPosition + "," +
                 "checksum=" + checksum( this ) +
                 "]";

enterprise/core-edge/src/main/java/org/neo4j/coreedge/raft/RaftInstance.java

@@ -95,7 +95,6 @@ public enum Timeouts implements RenewableTimeoutService.TimeoutName
     private Role currentRole = Role.FOLLOWER;
 
     private RaftLogShippingManager<MEMBER> logShipping;
-    private Set<Listener<LeadershipChange<MEMBER>>> leadershipChangeListeners = new HashSet<>();
 
     public RaftInstance( MEMBER myself, TermStore termStore, VoteStore<MEMBER> voteStore, RaftLog entryLog,
                          long electionTimeout, long heartbeatInterval, RenewableTimeoutService renewableTimeoutService,
@@ -200,23 +199,6 @@ public ReadableRaftState<MEMBER> state()
         return state;
     }
 
-    /**
-     * These listeners will be notified from within the raft, so they should be short, efficient and
-     * not have dependencies on raft. Any substantial work must be scheduled on a some other thread.
-     */
-    public void registerLeadershipChangeListener( Listener<LeadershipChange<MEMBER>> listener )
-    {
-        leadershipChangeListeners.add( listener );
-    }
-
-    private void notifyListenersOnLeadershipChange( MEMBER newLeader )
-    {
-        for ( Listener<LeadershipChange<MEMBER>> listener : leadershipChangeListeners )
-        {
-            listener.receive( new LeadershipChange<>( newLeader ) );
-        }
-    }
-
     protected void handleOutcome( Outcome<MEMBER> outcome ) throws RaftStorageException
     {
         // Save interesting pre-state
@@ -241,12 +223,6 @@ else if ( oldLeader != null && oldLeader.equals( myself ) && !outcome.getLeader(
 
         // Update state
         state.update( outcome );
-
-        // Act after updating state
-        if ( oldLeader != state.leader() )
-        {
-            notifyListenersOnLeadershipChange( state.leader() );
-        }
     }
 
     public synchronized void handle( Serializable incomingMessage )