[e2e] : Change default to fx_importer. (#4387)

Since torchscript path is not maintained anymore, updating the default
choice for e2e testing to `fx_importer` from `linalg`. Backend being
tested is still the `linalg` path.
Fixes #4386

Author: sahas3

docs/development.md

@@ -507,8 +507,8 @@ The following assumes you are in the `projects/pt1`  directory:
 ./tools/e2e_test.sh
 # Run tests that match the regex `Conv2d`, with verbose errors.
 ./tools/e2e_test.sh --filter Conv2d --verbose
-# Run tests on the TOSA backend.
-./tools/e2e_test.sh --config tosa
+# Run tests on the TOSA backend via fx_importer path
+./tools/e2e_test.sh --config fx_importer_tosa
 ```
 
 Alternatively, you can run the tests via Python directly:

projects/pt1/e2e_testing/main.py

@@ -86,12 +86,12 @@ def _get_argparse():
         "-c",
         "--config",
         choices=config_choices,
-        default="linalg",
+        default="fx_importer",
         help=f"""
 Meaning of options:
-"linalg": run through torch-mlir"s default Linalg-on-Tensors backend.
-"tosa": run through torch-mlir"s default TOSA backend.
-"stablehlo": run through torch-mlir"s default Stablehlo backend.
+"linalg": run the model through JIT importer frontend with torchscript (deprecated) and execute the graph using Linalg-on-Tensors backend.
+"tosa": run the model through JIT importer frontend with torchscript (deprecated) and execute the graph using TOSA backend.
+"stablehlo": run the model through JIT importer frontend with torchscript (deprecated) and execute the graph using Stablehlo backend.
 "native_torch": run the torch.nn.Module as-is without compiling (useful for verifying model is deterministic; ALL tests should pass in this configuration).
 "torchscript": compile the model to a torch.jit.ScriptModule, and then run that as-is (useful for verifying TorchScript is modeling the program correctly).
 "lazy_tensor_core": run the model through the Lazy Tensor Core frontend and execute the traced graph.