Fix NPE when accessing group concurrently

Closes #40368

# Conflicts:
#	tests/base/src/test/java/org/keycloak/tests/admin/group/GroupTest.java

Signed-off-by: vramik <vramik@redhat.com>

model/infinispan/src/main/java/org/keycloak/models/cache/infinispan/GroupAdapter.java

@@ -259,7 +259,8 @@ public class GroupAdapter implements GroupModel {
     @Override
     public Long getSubGroupsCount() {
         if (isUpdated()) return updated.getSubGroupsCount();
-        return getGroupModel().getSubGroupsCount();
+        GroupModel model = modelSupplier.get();
+        return model == null ? null : model.getSubGroupsCount();
     }
 
     @Override

model/infinispan/src/main/java/org/keycloak/models/cache/infinispan/entities/CachedGroup.java

@@ -56,6 +56,7 @@ public class CachedGroup extends AbstractRevisioned implements InRealm {
         this.type = group.getType();
     }
 
+    @Override
     public String getRealm() {
         return realm;
     }

services/src/main/java/org/keycloak/utils/GroupUtils.java

@@ -90,14 +90,4 @@ public class GroupUtils {
         rep.setAccess(groupsEvaluator.getAccess(groupTree));
         return rep;
     }
-
-    private static boolean groupMatchesSearchOrIsPathElement(GroupModel group, String search) {
-        if (StringUtil.isBlank(search)) {
-            return true;
-        }
-        if (group.getName().contains(search)) {
-            return true;
-        }
-        return group.getSubGroupsStream().findAny().isPresent();
-    }
 }