Stub tests migration part 4 (neo4j#847)

Removed RoutingDriverMultidatabaseBoltKitIT

Migrated tests:
- shouldDiscoverForDatabase -> test_should_read_successfully_from_reader_using_session_run (this tests seems to cover the same use-case and uses a non-default DB for 4+ versions)
- shouldRetryOnEmptyDiscoveryResult -> test_should_read_successfully_on_empty_discovery_result_using_session_run
- shouldThrowRoutingErrorIfDatabaseNotFound -> test_should_fail_with_routing_failure_on_db_not_found_discovery_failure
- shouldBeAbleToServeReachableDatabase -> test_should_read_successfully_from_reachable_db_after_trying_unreachable_db (message check has been removed)
- shouldPassSystemBookmarkWhenGettingRoutingTableForMultiDB -> test_should_pass_system_bookmark_when_getting_rt_for_multi_db (seems to be applicable to V4 only, also the stub server doesn't seem to check bookmarks)
- shouldIgnoreSystemBookmarkWhenGettingRoutingTable -> test_should_ignore_system_bookmark_when_getting_rt_for_multi_db
- shouldDriverVerifyConnectivity -> test_should_successfully_get_routing_table_with_context (pre-existing test that already tests the connectivity)

Also removed redundant scripts and added code support to DriverError

Author: injectives

driver/src/test/java/org/neo4j/driver/integration/RoutingDriverMultidatabaseBoltKitIT.java

@@ -175,7 +175,13 @@ else if ( currentLine.equals( "#request end" ) )
 
     private DriverError driverError( String id, Neo4jException e )
     {
-        return DriverError.builder().data( DriverError.DriverErrorBody.builder().id( id ).errorType( e.getClass().getName() ).build() ).build();
+        return DriverError.builder().data(
+                DriverError.DriverErrorBody.builder()
+                                           .id( id )
+                                           .errorType( e.getClass().getName() )
+                                           .code( e.code() )
+                                           .build() )
+                          .build();
     }
 
     public void processRequest( String request )

driver/src/test/resources/acquire_endpoints_v4.script

@@ -43,5 +43,7 @@ public static class DriverErrorBody
         private String id;
 
         private String errorType;
+
+        private String code;
     }
 }