[Relax][PyTorch] Enable run_ep_decomposition by default (#18471)

## Why

We have finished the migration for our tests then we could set default
to run ep decompose.

## How

Update tests and exported_program_translator.py

Author: guan404ming

python/tvm/relax/frontend/torch/exported_program_translator.py

@@ -208,6 +208,15 @@ def _native_group_norm(self, node: fx.Node) -> relax.Var:
             )
         )
 
+    def _native_layer_norm(self, node: fx.Node) -> relax.Var:
+        # native_layer_norm signature: (input, normalized_shape, weight, bias, eps)
+        x = self.env[node.args[0]]
+        normalized_shape = node.args[1]
+        gamma = self.env.get(node.args[2], None) if len(node.args) > 2 else None
+        beta = self.env.get(node.args[3], None) if len(node.args) > 3 else None
+        eps = node.args[4] if len(node.args) > 4 else 1e-05
+        return self._layer_norm_impl(x, gamma, beta, eps, normalized_shape)
+
     def _upsample_impl(
         self,
         x: relax.Expr,
@@ -1058,6 +1067,7 @@ def create_convert_map(
             "instance_norm.default": self._instance_norm,
             "native_group_norm.default": self._native_group_norm,
             "layer_norm.default": self._layer_norm,
+            "native_layer_norm.default": self._native_layer_norm,
             "linear.default": self._linear,
             "lstm.input": self._lstm,
             "gru.input": self._gru,
@@ -1403,7 +1413,7 @@ def from_exported_program(
     keep_params_as_input: bool = False,
     unwrap_unit_return_tuple: bool = False,
     no_bind_return_tuple: bool = False,
-    run_ep_decomposition: bool = False,
+    run_ep_decomposition: bool = True,
 ) -> tvm.IRModule:
     """Convert a PyTorch ExportedProgram to a Relax program
 
@@ -1426,8 +1436,7 @@ def from_exported_program(
     run_ep_decomposition : bool
         A boolean flag indicating whether to run PyTorch's decomposition on the
         exported program before translation. When True, high-level operators will
-        be decomposed into their constituent parts. Defaults to False for backward
-        compatibility.
+        be decomposed into their constituent parts. Defaults to True.
 
     Returns
     -------