[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/function_symbol/TestDisasmAPI.py

@@ -24,7 +24,6 @@ class DisasmAPITestCase(TestBase):
         self.line2 = line_number(
             'main.c', '// Find the line number for breakpoint 2 here.')
 
-    @add_test_categories(['pyapi'])
     @expectedFailureAll(oslist=["windows"], bugnumber='llvm.org/pr21765')
     def test(self):
         """Exercise getting SBAddress objects, disassembly, and SBAddress APIs."""