[Dy2stat] Add CycleGAN model for unitttest (#25072)

* add cycle_gan_model

* align train test=develop

* modify image_size into 64 to avoid TimeOut test=develop

* TODO in GPU test=develop

python/paddle/fluid/dygraph/dygraph_to_static/partial_program.py

@@ -110,11 +110,13 @@ class PartialProgramLayer(layers.Layer):
         self._inputs = NestSequence(inputs)
         self._outputs = NestSequence(outputs, need_check=True)
         self._params = parameters if parameters is not None else []
+
         # Check all params from main program can be found in self._params:
         # 1. parameter in self._params should be type `framework.ParamBase` which are created in dygraph.
         # 2. parameter from transformed program shall be found in self._params.
         #    Because they share same data with ParamBase of original dygraph.
         self._check_params_all_inited(main_program)
+        self._prune_unused_params(main_program)
 
         self._infer_program = main_program
         self._train_program = self._append_backward_desc()
@@ -138,6 +140,23 @@ class PartialProgramLayer(layers.Layer):
 
         return program
 
+    def _prune_unused_params(self, program):
+        """
+        Prune the parameters not used anywhere in the program.
+        The `@declarative` may only decorated a sub function which
+        contains some unused parameters created in `__init__`.
+        So prune these parameters to avoid unnecessary operations in
+        `run_program_op`.
+        """
+        required_params = []
+        for param in self._params:
+            for block in program.blocks:
+                if param.name in block.vars:
+                    required_params.append(param)
+                    break
+
+        self._params = required_params
+
     def train(self):
         # self.training is inherited from layers.Layer
         self.training = True