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}
diff --git a/testing/merge_scripts/standard_gtest_merge_test.py b/testing/merge_scripts/standard_gtest_merge_test.py
index e39fe9c9..05ea01f 100755
--- a/testing/merge_scripts/standard_gtest_merge_test.py
+++ b/testing/merge_scripts/standard_gtest_merge_test.py
@@ -7,21 +7,14 @@
 import logging
 import os
 import shutil
-import six
 import sys
 import tempfile
 import unittest
+from unittest import mock
 
-import common_merge_script_tests
 import six
 
-THIS_DIR = os.path.dirname(os.path.abspath(__file__))
-
-# For 'standard_gtest_merge.py'.
-sys.path.insert(0, os.path.abspath(os.path.join(THIS_DIR, '..', 'resources')))
-
-import mock
-
+import common_merge_script_tests
 import standard_gtest_merge
 
 # gtest json output for successfully finished shard #0.