feature_table: Add feature barrier for force reconfiguration API.

src/v/features/feature_table.cc

@@ -77,6 +77,8 @@ std::string_view to_string_view(feature f) {
         return "cloud_storage_manifest_format_v2";
     case feature::transaction_partitioning:
         return "transaction_partitioning";
+    case feature::force_partition_reconfiguration:
+        return "force_partition_reconfiguration";
 
     /*
      * testing features

src/v/features/feature_table.h

@@ -58,6 +58,7 @@ enum class feature : std::uint64_t {
     controller_snapshots = 1ULL << 23U,
     cloud_storage_manifest_format_v2 = 1ULL << 24U,
     transaction_partitioning = 1ULL << 25U,
+    force_partition_reconfiguration = 1ULL << 26U,
 
     // Dummy features for testing only
     test_alpha = 1ULL << 62U,
@@ -267,6 +268,12 @@ constexpr static std::array feature_schema{
     feature::transaction_partitioning,
     feature_spec::available_policy::always,
     feature_spec::prepare_policy::always},
+  feature_spec{
+    cluster::cluster_version{10},
+    "force_partition_reconfiguration",
+    feature::force_partition_reconfiguration,
+    feature_spec::available_policy::always,
+    feature_spec::prepare_policy::always},
 
   // For testing, a feature that does not auto-activate
   feature_spec{

src/v/redpanda/admin_server.cc

@@ -2810,8 +2810,13 @@ admin_server::unclean_abort_partition_reconfig_handler(
 ss::future<ss::json::json_return_type>
 admin_server::force_set_partition_replicas_handler(
   std::unique_ptr<ss::http::request> req) {
-    auto ntp = parse_ntp_from_request(req->param);
+    if (unlikely(!_controller->get_feature_table().local().is_active(
+          features::feature::force_partition_reconfiguration))) {
+        throw ss::httpd::bad_request_exception(
+          "Feature not active yet, upgrade in progress?");
+    }
 
+    auto ntp = parse_ntp_from_request(req->param);
     if (ntp == model::controller_ntp) {
         throw ss::httpd::bad_request_exception(
           fmt::format("Can't reconfigure a controller"));