Revert "pythongh-107265: Ensure _PyCode_Quicken does not handle ENTER_EXECUTOR (pythongh-108460)"

This reverts commit d6ac5c7.

Author: corona10

Python/specialize.c

@@ -300,8 +300,6 @@ _PyCode_Quicken(PyCodeObject *code)
     for (int i = 0; i < Py_SIZE(code); i++) {
         opcode = _Py_GetBaseOpcode(code, i);
         assert(opcode < MIN_INSTRUMENTED_OPCODE);
-        // _PyCode_Quicken is only called when initializing a fresh code object.
-        assert(opcode != ENTER_EXECUTOR);
         int caches = _PyOpcode_Caches[opcode];
         if (caches) {
             instructions[i + 1].cache = adaptive_counter_warmup();