Bug: SAM CLI tries to import packages from system Python on Windows

### Description:

When I run `sam local` or any other SAM command, they all fail:
```
sam local
2024-09-21 22:45:29 Command 'local' is not configured correctly. Unable to import 'samcli.commands.local.local'
Traceback (most recent call last):
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\cli\command.py", line 264, in get_command
mod = importlib.import_module(pkg_name)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "importlib\__init__.py", line 90, in import_module
File "", line 1387, in _gcd_import
File "", line 1360, in _find_and_load
File "", line 1331, in _find_and_load_unlocked
File "", line 935, in _load_unlocked
File "", line 995, in exec_module
File "", line 488, in _call_with_frames_removed
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\commands\local\local.py", line 8, in
from .generate_event.cli import cli as generate_event_cli
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\commands\local\generate_event\cli.py", line 8, in
from samcli.commands.local.generate_event.core.command import CoreGenerateEventCommand
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\commands\local\generate_event\core\command.py", line 10, in
from samcli.commands.local.generate_event.event_generation import GenerateEventCommand
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\commands\local\generate_event\event_generation.py", line 12, in
from samcli.lib.telemetry.metric import track_command
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\lib\telemetry\metric.py", line 22, in
from samcli.lib.hook.hook_config import HookPackageConfig
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\samcli\lib\hook\hook_config.py", line 7, in
import jsonschema
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\jsonschema\__init__.py", line 13, in
from jsonschema._format import FormatChecker
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\jsonschema\_format.py", line 11, in
from jsonschema.exceptions import FormatError
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\jsonschema\exceptions.py", line 14, in
from attrs import define
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages\attrs\__init__.py", line 3, in
from attr import (
ImportError: cannot import name 'AttrsInstance' from 'attr' (C:\Users\myuser\AppData\Roaming\Python\Python312\site-packages\attr\__init__.py)
Usage: sam [OPTIONS] COMMAND [ARGS]...
Try 'sam -h' for help.

Error: No such command 'local'.
```

It seems that the `attr` package is supposed to be read from `C:\Program Files\Amazon\AWSSAMCLI\runtime\Lib\site-packages` but instead it is read from the user packages folder at `C:\Users\\AppData\Roaming\Python\Python312\site-packages`.

### Steps to reproduce:

1. Install Python 3.12
2. Add it to user's `PATH` environment variable
3. Install SAM CLI
4. Install the `attrs` package: `pip install --user attrs==18.1.0`

Note: `C:\Program Files\Amazon\AWSSAMCLI\bin` comes before `C:\Program Files\Python312` in `PATH` - I double checked.

### Observed result:

SAM commands don't work.

### Expected result:

Expected them to not use my Python installation but use the one that ships with the installer.

### Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

1. OS: Windows 10
5. `sam --version`: `SAM CLI, version 1.124.0`
6. AWS region: -

```
{
"version": "1.124.0",
"system": {
"python": "3.12.6",
"os": "Windows-10-10.0.19045-SP0"
},
"additional_dependencies": {
"docker_engine": "Not available",
"aws_cdk": "Not available",
"terraform": "Not available"
},
"available_beta_feature_env_vars": [
"SAM_CLI_BETA_FEATURES",
"SAM_CLI_BETA_BUILD_PERFORMANCE",
"SAM_CLI_BETA_TERRAFORM_SUPPORT",
"SAM_CLI_BETA_RUST_CARGO_LAMBDA"
]
}
```

Python version: 3.12.6