Revert "SERVER-14458 swap LegacyReplicationCoordinator for the HybridReplicationCoordinator"

This reverts commit 249c0a5.

Author: matt dannenberg

src/mongo/SConscript

@@ -575,7 +575,6 @@ serverOnlyFiles = [ "db/curop.cpp",
                     "db/repl/rs.cpp",
                     "db/repl/consensus.cpp",
                     "db/repl/rs_initiate.cpp",
-                    "db/repl/repl_coordinator_hybrid.cpp",
                     "db/repl/repl_coordinator_legacy.cpp",
                     "db/repl/repl_set_seed_list.cpp",
                     "db/repl/repl_set_health_poll_task.cpp",

src/mongo/db/db.cpp

@@ -70,8 +70,8 @@
 #include "mongo/db/repair_database.h"
 #include "mongo/db/repl/network_interface_impl.h"
 #include "mongo/db/repl/repl_coordinator_global.h"
-#include "mongo/db/repl/repl_coordinator_hybrid.h"
 #include "mongo/db/repl/repl_coordinator_impl.h"
+#include "mongo/db/repl/repl_coordinator_legacy.h"
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/repl/rs.h"
 #include "mongo/db/repl/topology_coordinator_impl.h"
@@ -827,6 +827,12 @@ MONGO_INITIALIZER(SetGlobalConfigExperiment)(InitializerContext* context) {
     return Status::OK();
 }
 
+namespace {
+    // TODO(spencer): Remove this startup parameter once the new ReplicationCoordinator is fully
+    // working
+    MONGO_EXPORT_STARTUP_SERVER_PARAMETER(useNewReplCoordinator, bool, false);
+} // namespace
+
 namespace {
     repl::ReplSettings replSettings;
 } // namespace
@@ -837,8 +843,14 @@ namespace mongo {
     }
 } // namespace mongo
 
-MONGO_INITIALIZER(CreateReplicationManager)(InitializerContext* context) {
-    repl::setGlobalReplicationCoordinator(new repl::HybridReplicationCoordinator(replSettings));
+MONGO_INITIALIZER(CreateReplicationCoordinator)(InitializerContext* context) {
+    if (useNewReplCoordinator) {
+        repl::setGlobalReplicationCoordinator(
+                new repl::ReplicationCoordinatorImpl(replSettings));
+    } else {
+        repl::setGlobalReplicationCoordinator(
+                new repl::LegacyReplicationCoordinator(replSettings));
+    }
     return Status::OK();
 }