Remove ObjectPool leak flag from GroupDataProviderImpl::mKeySetIterat…

…ors (#12734)

#### Problem

The `ObjectPool` leak reported in #12503 _ObjectPool leaks in
GroupDataProviderImpl_ is no longer reproducable; possibly fixed
by d25a3ef.

#### Change overview

Remove the ‘allow leaks’ flag from `GroupDataProviderImpl::mKeySetIterators`.

#### Testing

CI.

src/credentials/GroupDataProviderImpl.h

@@ -160,7 +160,7 @@ class GroupDataProviderImpl : public GroupDataProvider
     BitMapObjectPool<GroupMappingIteratorImpl, kIteratorsMax> mEndpointGroupsIterators;
     BitMapObjectPool<AllStatesIterator, kIteratorsMax> mAllStatesIterators;
     BitMapObjectPool<FabricStatesIterator, kIteratorsMax> mFabricStatesIterators;
-    BitMapObjectPool<KeySetIteratorImpl, kIteratorsMax, OnObjectPoolDestruction::IgnoreUnsafeDoNotUseInNewCode> mKeySetIterators;
+    BitMapObjectPool<KeySetIteratorImpl, kIteratorsMax> mKeySetIterators;
 };
 
 } // namespace Credentials