redpanda/main: use scheduling groups probe

This commit wires up a scheduling_groups_probe in order to publish
metrics based on the scheduling groups stats. Note how the probe is
cleared before the scheduling groups are destroyed to prevent publishing
metrics from a destroyed group.

src/v/redpanda/application.cc

@@ -294,8 +294,11 @@ void application::initialize(
     }
 
     _scheduling_groups.create_groups().get();
-    _deferred.emplace_back(
-      [this] { _scheduling_groups.destroy_groups().get(); });
+    _scheduling_groups_probe.wire_up(_scheduling_groups);
+    _deferred.emplace_back([this] {
+        _scheduling_groups_probe.clear();
+        _scheduling_groups.destroy_groups().get();
+    });
 
     if (proxy_cfg) {
         _proxy_config.emplace(*proxy_cfg);

src/v/redpanda/application.h

@@ -31,6 +31,7 @@
 #include "redpanda/admin_server.h"
 #include "resource_mgmt/cpu_scheduling.h"
 #include "resource_mgmt/memory_groups.h"
+#include "resource_mgmt/scheduling_groups_probe.h"
 #include "resource_mgmt/smp_groups.h"
 #include "rpc/fwd.h"
 #include "seastarx.h"
@@ -157,6 +158,7 @@ class application {
       _schema_reg_config;
     std::optional<kafka::client::configuration> _schema_reg_client_config;
     scheduling_groups _scheduling_groups;
+    scheduling_groups_probe _scheduling_groups_probe;
     ss::logger _log;
 
     ss::sharded<rpc::connection_cache> _connection_cache;