[CustomOp] Add Modeling with Custom op unittest (#31218)

* add unittest for static/dygraph/dy2stat

* add PE unittet

* remove usless code

* add unittest in CMakeList.txt

python/paddle/fluid/tests/custom_op/CMakeLists.txt

@@ -3,10 +3,12 @@ if(WITH_GPU)
     # 'test_custom_relu_op_setup/jit' compile .cc and .cu file
     py_test(test_custom_relu_op_setup SRCS test_custom_relu_op_setup.py)
     py_test(test_custom_relu_op_jit SRCS test_custom_relu_op_jit.py)
+    py_test(test_custom_relu_model SRCS test_custom_relu_model.py)
 
     # Compiling shared library will cost some time, but running process is very fast.
     set_tests_properties(test_custom_relu_op_setup PROPERTIES TIMEOUT 250)
     set_tests_properties(test_custom_relu_op_jit PROPERTIES TIMEOUT 180)
+    set_tests_properties(test_custom_relu_model PROPERTIES TIMEOUT 180)
 endif()
 
 py_test(test_sysconfig SRCS test_sysconfig.py)