fix "Connect multiple replicas at the same time" test (redis#10294)

In order to make sure no more commands processed, we wait that
the 'load handlers' will disconncet.

The test by mistake waited on the (last) slave instead of the master.

Author: YaacovHazan

tests/integration/replication.tcl

@@ -318,7 +318,7 @@ foreach mdl {no yes} {
                             stop_write_load $load_handle4
 
                             # Make sure no more commands processed
-                            wait_load_handlers_disconnected
+                            wait_load_handlers_disconnected -3
 
                             wait_for_ofs_sync $master [lindex $slaves 0]
                             wait_for_ofs_sync $master [lindex $slaves 1]