[3.13] gh-139640: Fix swallowing syntax warnings in different modules (GH-139755) (GH-140119)

Revert GH-131993.

Fix swallowing some syntax warnings in different modules if they accidentally
have the same message and are emitted from the same line.

Fix duplicated warnings in the "finally" block.

(cherry picked from commit 279db6bede)

Include/cpython/warnings.h

@@ -18,9 +18,3 @@ PyAPI_FUNC(int) PyErr_WarnExplicitFormat(
 
 // DEPRECATED: Use PyErr_WarnEx() instead.
 #define PyErr_Warn(category, msg) PyErr_WarnEx((category), (msg), 1)
-
-int _PyErr_WarnExplicitObjectWithContext(
-    PyObject *category,
-    PyObject *message,
-    PyObject *filename,
-    int lineno);