[lldb/tests] Removed add_test_categories decorator for python API tests, NFC

There is a .categories file in the python_api directory that makes all nested tests
belong to the category "pyapi". The decorator is unnecessary for these tests.

lldb/test/API/python_api/frame/inlines/TestInlinedFrame.py

@@ -25,7 +25,6 @@ class InlinedFrameAPITestCase(TestBase):
         self.second_stop = line_number(
             self.source, '// This should correspond to the second break stop.')
 
-    @add_test_categories(['pyapi'])
     def test_stop_at_outer_inline(self):
         """Exercise SBFrame.IsInlined() and SBFrame.GetFunctionName()."""
         self.build()