Stricter settings in mypy_test (#9294)

tests/mypy_test.py

@@ -251,10 +251,11 @@ def get_mypy_flags(args: TestConfig, temp_name: str, *, testing_stdlib: bool) ->
         "--no-site-packages",
         "--custom-typeshed-dir",
         str(Path(__file__).parent.parent),
-        "--no-implicit-optional",
-        "--disallow-untyped-decorators",
-        "--disallow-any-generics",
-        "--strict-equality",
+        "--strict",
+        # Stub completion is checked by pyright (--allow-*-defs)
+        "--allow-untyped-defs",
+        "--allow-incomplete-defs",
+        "--allow-subclassing-any",  # Needed until we can use non-types dependencies #5768
         "--enable-error-code",
         "ignore-without-code",
         "--config-file",