Auto merge of #12313 - cynicaldevil:tidy-test, r=Wafflespeanut

test-tidy command now ignores files in subdirectories of ignored dirs

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12225 .

I did not add a test for this, instead I added a directory with an empty file inside the ignored directory, and checked whether this file was being ignored or not.

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python/tidy/servo_tidy/tidy.py

@@ -636,7 +636,7 @@ def get_file_list(directory, only_changed_files=False, exclude_dirs=[]):
         args = ["git", "ls-files", "--others", "--exclude-standard", directory]
         file_list += subprocess.check_output(args)
         for f in file_list.splitlines():
-            if os.path.join('.', os.path.dirname(f)) not in exclude_dirs:
+            if not any(os.path.join('.', os.path.dirname(f)).startswith(path) for path in exclude_dirs):
                 yield os.path.join('.', f)
     elif exclude_dirs:
         for root, dirs, files in os.walk(directory, topdown=True):