Reland "Fix //testing import lint issues"

This is a reland of commit a418670f47e2a8bb3a2ce69e990203eb69b5225f

Changes from original CL:
* Fixed run_variations_smoke_test.py being unable to import
  from //build

Original change's description:
> Fix //testing import lint issues
>
> Removes the import-related entries from //testing's pylintrc file and
> fixes resulting lint errors.
>
> Bug: 353942917
> Change-Id: Ie3b3dba795e0806631c37243a3b4f480a4215a6e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5737567
> Auto-Submit: Brian Sheedy <[email protected]>
> Commit-Queue: Brian Sheedy <[email protected]>
> Reviewed-by: Ben Pastene <[email protected]>
> Cr-Commit-Position: refs/heads/main@{#1337485}

Bug: 353942917
Change-Id: Id9495cb75529fcc76037070abb4837d45f94210f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5766912
Reviewed-by: Ben Pastene <[email protected]>
Commit-Queue: Ben Pastene <[email protected]>
Auto-Submit: Brian Sheedy <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1338093}
NOKEYCHECK=True
GitOrigin-RevId: c0021a86cb08d9c5fa63382560506a9967a056a0
diff --git a/exe_util.py b/exe_util.py
index 0b61ad3..4d63446 100644
--- a/exe_util.py
+++ b/exe_util.py
@@ -4,7 +4,6 @@
 """Utilities for invoking executables.
 """
 
-import os
 import subprocess
 import re
 import sys
diff --git a/exe_util_unittests.py b/exe_util_unittests.py
index 679afa3..9b16978 100755
--- a/exe_util_unittests.py
+++ b/exe_util_unittests.py
@@ -4,13 +4,9 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import argparse
-import json
-import os
-from pyfakefs import fake_filesystem_unittest
 import sys
-import tempfile
-import unittest
+
+from pyfakefs import fake_filesystem_unittest
 
 import exe_util
 
diff --git a/generate_script.py b/generate_script.py
index 2cd58c7..ec5fa95 100755
--- a/generate_script.py
+++ b/generate_script.py
@@ -11,6 +11,7 @@
 sys.path.append(
     os.path.join(os.path.dirname(__file__), os.pardir, os.pardir, os.pardir,
                  'build'))
+# //build imports.
 import action_helpers
 
 
diff --git a/generate_script_unittests.py b/generate_script_unittests.py
index f875dac..c627731 100755
--- a/generate_script_unittests.py
+++ b/generate_script_unittests.py
@@ -5,10 +5,11 @@
 # found in the LICENSE file.
 
 import os
-from pyfakefs import fake_filesystem_unittest
 import tempfile
 import unittest
 
+from pyfakefs import fake_filesystem_unittest
+
 from generate_script import _parse_args
 from generate_script import _generate_script
 
diff --git a/main_program.py b/main_program.py
index 3c93e59..e585f3c 100644
--- a/main_program.py
+++ b/main_program.py
@@ -26,7 +26,6 @@
             test_executable_wrappers, parsed_cmdline_args, os.environ)
 """
 
-import argparse
 import time
 
 import test_filtering
diff --git a/main_program_unittests.py b/main_program_unittests.py
index 57cb3d5..89e8f8f 100755
--- a/main_program_unittests.py
+++ b/main_program_unittests.py
@@ -7,11 +7,11 @@
 import argparse
 import json
 import os
-from pyfakefs import fake_filesystem_unittest
-import sys
 import tempfile
 import unittest
 
+from pyfakefs import fake_filesystem_unittest
+
 from test_results import TestResult
 
 import main_program
diff --git a/rust_main_program.py b/rust_main_program.py
index db156d8..69b8c87 100644
--- a/rust_main_program.py
+++ b/rust_main_program.py
@@ -11,7 +11,6 @@
 import subprocess
 import sys
 
-sys.path.append(os.path.dirname(os.path.abspath(__file__)))
 import exe_util
 import main_program
 import test_results
diff --git a/rust_main_program_unittests.py b/rust_main_program_unittests.py
index c8861de..d529cd4 100755
--- a/rust_main_program_unittests.py
+++ b/rust_main_program_unittests.py
@@ -5,10 +5,11 @@
 # found in the LICENSE file.
 
 import os
-from pyfakefs import fake_filesystem_unittest
 import tempfile
 import unittest
 
+from pyfakefs import fake_filesystem_unittest
+
 from test_results import TestResult
 
 from rust_main_program import _format_test_name
diff --git a/test_filtering.py b/test_filtering.py
index 43ec6ad..38b3e75 100644
--- a/test_filtering.py
+++ b/test_filtering.py
@@ -19,10 +19,7 @@
         parsed_cmdline_args, list_of_all_test_names)
 """
 
-import argparse
-import os
 import re
-import sys
 
 
 class _TestFilter:
diff --git a/test_filtering_unittests.py b/test_filtering_unittests.py
index 8fa13fa..51c7464 100755
--- a/test_filtering_unittests.py
+++ b/test_filtering_unittests.py
@@ -6,10 +6,11 @@
 
 import argparse
 import os
-from pyfakefs import fake_filesystem_unittest
 import tempfile
 import unittest
 
+from pyfakefs import fake_filesystem_unittest
+
 import test_filtering
 from test_filtering import _TestFilter
 from test_filtering import _TestFiltersGroup