Using ./sage -fiximports from #34945.

Also remove trailing whitespace in the affected files.

Part of Meta-ticket #34201

CC: @alexchandler100 @dcoudert @dimpase

Component: refactoring

Author: Alex Chandler

Branch/Commit: u/mkoeppe/sage_graphs__replace_imports_from_sage___all_for_namespace_packages @ 180c16b

Reviewer: David Coudert

Issue created by migration from https://trac.sagemath.org/ticket/34952