[3.10] bpo-45229: Remove test_main in many tests (GH-28405) (GH-28455)

Instead of explicitly enumerate test classes for run_unittest()
use the unittest ability to discover tests. This also makes these
tests discoverable and runnable with unittest.

load_tests() can be used for dynamic generating tests and adding
doctests. setUpModule(), tearDownModule() and addModuleCleanup()
can be used for running code before and after all module tests.
(cherry picked from commit 40348acc180580371d25f75f46b27048e35f2435)
diff --git a/Lib/test/test_bool.py b/Lib/test/test_bool.py
index a3214c9..4b32aad 100644
--- a/Lib/test/test_bool.py
+++ b/Lib/test/test_bool.py
@@ -1,7 +1,6 @@
 # Test properties of bool promised by PEP 285
 
 import unittest
-from test import support
 from test.support import os_helper
 
 import os
@@ -370,8 +369,6 @@ def f(x):
         f(x)
         self.assertGreaterEqual(x.count, 1)
 
-def test_main():
-    support.run_unittest(BoolTest)
 
 if __name__ == "__main__":
-    test_main()
+    unittest.main()