Remove unnecessary std::move() calls.
Remove unnecessary std::move() calls.

This fixes the following build error:

```
ERROR: /tf/xla/xla/service/gpu/tests/BUILD:939:9: Compiling xla/service/gpu/tests/gpu_fused_mha_test.cc failed: (Exit 1): clang failed: error executing command (from target //xla/service/gpu/tests:gpu_fused_mha_test_gpu) /usr/lib/llvm-17/bin/clang -MD -MF bazel-out/k8-opt/bin/xla/service/gpu/tests/_objs/gpu_fused_mha_test_gpu/gpu_fused_mha_test.d ... (remaining 345 arguments skipped)
xla/service/gpu/tests/gpu_fused_mha_test.cc:121:24: error: moving a temporary object prevents copy elision [-Werror,-Wpessimizing-move]
  121 |         CountFMHACalls(std::move(reference_module->Clone())));
      |                        ^
xla/service/gpu/tests/gpu_fused_mha_test.cc:129:44: error: moving a temporary object prevents copy elision [-Werror,-Wpessimizing-move]
  129 |                             CountFMHACalls(std::move(test_module->Clone())));
      |                                            ^
2 errors generated.
```
