fix: Fix unsafe_local_code_executor for import scope

Merge #869

How to reproduce the error:

```
from google.adk.code_executors import UnsafeLocalCodeExecutor
from google.adk.code_executors.code_execution_utils import CodeExecutionInput

result = UnsafeLocalCodeExecutor().execute_code(
    invocation_context=None,
    code_execution_input=CodeExecutionInput(
        code='''
import math

def pi():
    return math.pi

print(pi())
'''
    )
)

print(result)
```

output:
```
CodeExecutionResult(stdout='', stderr="name 'math' is not defined", output_files=[])
```
COPYBARA_INTEGRATE_REVIEW=#869 from qieqieplus:main 63f557b
PiperOrigin-RevId: 787145189

Author: qieqieplus

src/google/adk/code_executors/unsafe_local_code_executor.py

@@ -66,10 +66,9 @@ def execute_code(
     try:
       globals_ = {}
       _prepare_globals(code_execution_input.code, globals_)
-      locals_ = {}
       stdout = io.StringIO()
       with redirect_stdout(stdout):
-        exec(code_execution_input.code, globals_, locals_)
+        exec(code_execution_input.code, globals_)
       output = stdout.getvalue()
     except Exception as e:
       error = str(e)