Revert "SERVER-32051 Require shard servers and config servers to be replica sets"

This reverts commit e35e66b.

Part of SERVER-32080 as well.

Author: ramonfm

jstests/sharding/require_shardsvrs_and_configsvrs_to_be_replica_sets.js

@@ -148,7 +148,7 @@
     {
         jsTest.setOption('enableTestCommands', false);
 
-        var st = new ShardingTest({shards: 2, rs: true});
+        var st = new ShardingTest({shards: 2});
         var admin = st.s.getDB('admin');
 
         assert.commandWorked(

jstests/sharding/shard_config_db_collections.js

@@ -414,7 +414,6 @@ env.Library(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/db/storage/mmap_v1/mmap_v1_options',
-        'commands/test_commands_enabled',
         'repl/repl_settings',
         'server_options',
         'storage/storage_options',

src/mongo/db/SConscript

@@ -453,17 +453,16 @@ Status addMongodOptions(moe::OptionSection* options) {
                            "configsvr",
                            moe::Switch,
                            "declare this is a config db of a cluster; default port 27019; "
-                           "default dir /data/configdb; requires using --replSet")
+                           "default dir /data/configdb")
         .setSources(moe::SourceAllLegacy)
         .incompatibleWith("shardsvr")
         .incompatibleWith("nojournal");
 
     sharding_options
-        .addOptionChaining(
-            "shardsvr",
-            "shardsvr",
-            moe::Switch,
-            "declare this is a shard db of a cluster; default port 27018; requires using --replSet")
+        .addOptionChaining("shardsvr",
+                           "shardsvr",
+                           moe::Switch,
+                           "declare this is a shard db of a cluster; default port 27018")
         .setSources(moe::SourceAllLegacy)
         .incompatibleWith("configsvr")
         .incompatibleWith("master")
@@ -1199,14 +1198,6 @@ Status storeMongodOptions(const moe::Environment& params) {
     }
     if (params.count("sharding.clusterRole")) {
         auto clusterRoleParam = params["sharding.clusterRole"].as<std::string>();
-
-        if (!params.count("replication.replSet") && !Command::testCommandsEnabled) {
-            return {ErrorCodes::InvalidOptions,
-                    str::stream() << "Cannot start a " << clusterRoleParam
-                                  << " as a standalone server. Please start this node as a replica "
-                                     "set using --replSet."};
-        }
-
         if (clusterRoleParam == "configsvr") {
             serverGlobalParams.clusterRole = ClusterRole::ConfigServer;