[GPU] Fix segfault in layer tests for onnx_tests.test_lstm.TestLSTM (openvinotoolkit#26159)

### Details:
- This issue occurs after
openvinotoolkit#26032
 - Fix segfault in layer tests for onnx_tests.test_lstm.TestLSTM

### Tickets:
 - [CVS-150221](https://jira.devtools.intel.com/browse/CVS-150221)

Author: andrew-k-park

src/plugins/intel_gpu/src/graph/include/reshape_inst.h

@@ -44,7 +44,7 @@ struct typed_program_node<reshape> : public typed_program_node_base<reshape> {
             return false;
 
         // oneDNN supports padded input of outer axis only for buffer fusing on static shape
-        if (!has_outer_padding_offset() && get_users().front()->get_preferred_impl_type() == impl_types::onednn)
+        if (!has_outer_padding_offset() && get_users().size() == 1 && get_users().front()->get_preferred_impl_type() == impl_types::onednn)
             return false;
 
         // TODO: If user is RoPE or MVN and dynamic padding exists, ouput padding propagation is not supported in the base mode