python: skip pytest_pycollect_makeitem work on certain names

When a Python object (module/class/instance) is collected, for each name
in `obj.__dict__` (and up its MRO) the pytest_pycollect_makeitem hook is
called for potentially creating a node for it.

These Python objects have a bunch of builtin attributes that are
extremely unlikely to be collected. But due to their pervasiveness,
dispatching the hook for them ends up being mildly expensive and also
pollutes PYTEST_DEBUG=1 output and such.

Let's just ignore these attributes.

On the pandas test suite commit 04e9e0afd476b1b8bed930e47bf60e,
collect only, irrelevant lines snipped, about 5% improvement:

Before:

```
         51195095 function calls (48844352 primitive calls) in 39.089 seconds

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
226602/54    0.145    0.000   38.940    0.721 manager.py:90(_hookexec)
    72227    0.285    0.000   20.146    0.000 python.py:424(_makeitem)
    72227    0.171    0.000   16.678    0.000 python.py:218(pytest_pycollect_makeitem)
```

After:

```
          48410921 function calls (46240870 primitive calls) in 36.950 seconds

    ncalls  tottime  percall  cumtime  percall filename:lineno(function)
 181429/54    0.113    0.000   36.777    0.681 manager.py:90(_hookexec)
     27054    0.130    0.000   17.755    0.001 python.py:465(_makeitem)
     27054    0.121    0.000   16.219    0.001 python.py:218(pytest_pycollect_makeitem)
```

testing/python/collect.py

@@ -885,6 +885,34 @@ class TestConftestCustomization:
         result = testdir.runpytest_subprocess()
         result.stdout.fnmatch_lines(["*1 passed*"])
 
+    def test_early_ignored_attributes(self, testdir: Testdir) -> None:
+        """Builtin attributes should be ignored early on, even if
+        configuration would otherwise allow them.
+
+        This tests a performance optimization, not correctness, really,
+        although it tests PytestCollectionWarning is not raised, while
+        it would have been raised otherwise.
+        """
+        testdir.makeini(
+            """
+            [pytest]
+            python_classes=*
+            python_functions=*
+        """
+        )
+        testdir.makepyfile(
+            """
+            class TestEmpty:
+                pass
+            test_empty = TestEmpty()
+            def test_real():
+                pass
+        """
+        )
+        items, rec = testdir.inline_genitems()
+        assert rec.ret == 0
+        assert len(items) == 1
+
 
 def test_setup_only_available_in_subdir(testdir):
     sub1 = testdir.mkpydir("sub1")