Speed up the default plugin (#19462)

Use precalculated set objects in more places.

This is similar to #19385. Some cases were still unoptimized.

I used trace logging (#19457) to identify functions where we were
creating many set objects, and I noticed that these were unnecessary.

This is a part of a set of micro-optimizations that improve self check
performance by ~5.5%.

Author: JukkaL

mypy/plugins/default.py

@@ -82,6 +82,7 @@
 
 TD_SETDEFAULT_NAMES: Final = {n + ".setdefault" for n in TPDICT_FB_NAMES}
 TD_POP_NAMES: Final = {n + ".pop" for n in TPDICT_FB_NAMES}
+TD_DELITEM_NAMES: Final = {n + ".__delitem__" for n in TPDICT_FB_NAMES}
 
 TD_UPDATE_METHOD_NAMES: Final = (
     {n + ".update" for n in TPDICT_FB_NAMES}
@@ -144,11 +145,11 @@ def get_method_hook(self, fullname: str) -> Callable[[MethodContext], Type] | No
             return int_pos_callback
         elif fullname in ("builtins.tuple.__mul__", "builtins.tuple.__rmul__"):
             return tuple_mul_callback
-        elif fullname in {n + ".setdefault" for n in TPDICT_FB_NAMES}:
+        elif fullname in TD_SETDEFAULT_NAMES:
             return typed_dict_setdefault_callback
-        elif fullname in {n + ".pop" for n in TPDICT_FB_NAMES}:
+        elif fullname in TD_POP_NAMES:
             return typed_dict_pop_callback
-        elif fullname in {n + ".__delitem__" for n in TPDICT_FB_NAMES}:
+        elif fullname in TD_DELITEM_NAMES:
             return typed_dict_delitem_callback
         elif fullname == "_ctypes.Array.__getitem__":
             return array_getitem_callback