fix: Respect user-provided directory in Ansys Notebook (#4358)

This pull request updates the file download logic in the
`file_transfer_service.py` utility to improve how the local download
directory is handled. The changes ensure that if no local directory is
specified, the current working directory (`self.cwd`) is used by
default, and that files are always downloaded to the intended directory.

Improvements to file download handling:

* Changed the default value of the `local_directory` parameter in the
`download` method from `"."` to `None`, clarifying intent and allowing
explicit handling of the default directory.
* Updated the logic in the `download` method to set `download_directory`
to `self.cwd` if `local_directory` is not provided, ensuring consistent
download behavior.
* Modified file copy operations to use the resolved `download_directory`
instead of always using `self.cwd`, so files are placed in the correct
location as specified by the user.

---------

Co-authored-by: pyansys-ci-bot <[email protected]>

Author: hpohekar

doc/changelog.d/4358.fixed.md

@@ -0,0 +1 @@
+Respect user-provided directory in Ansys Notebook

src/ansys/fluent/core/utils/file_transfer_service.py

@@ -647,7 +647,7 @@ def download_file(self, file_name: str, local_directory: str | None = None):
             else:
                 raise FileNotFoundError("Remote file does not exist.")
 
-    def download(self, file_name: list[str] | str, local_directory: str | None = "."):
+    def download(self, file_name: list[str] | str, local_directory: str | None = None):
         """Download a file from the server.
 
         Parameters
@@ -657,22 +657,23 @@ def download(self, file_name: list[str] | str, local_directory: str | None = "."
         local_directory : str, optional
             Local directory. The default is the current working directory.
         """
+        download_directory = local_directory if local_directory else self.cwd
         files = [file_name] if isinstance(file_name, str) else file_name
         if self.is_configured():
             for file in files:
-                download_file_name = os.path.join(self.instance_dir, file)
                 if os.path.isfile(file):
                     warnings.warn(
                         f"\nFile already exists. File path:\n{file}\n",
                         PyFluentUserWarning,
                     )
                 else:
+                    download_file_name = os.path.join(self.instance_dir, file)
                     if os.path.exists(download_file_name):
-                        shutil.copy2(download_file_name, self.cwd)
+                        shutil.copy2(download_file_name, download_directory)
                     else:
                         self.download_file(
                             file_name=os.path.basename(file),
-                            local_directory=local_directory,
+                            local_directory=download_directory,
                         )
 
     def __call__(self, pim_instance: Any | None = None):