[red-knot] Fix descriptor __get__ call on class objects (#16304)

## Summary

I spotted a minor mistake in my descriptor protocol implementation where
`C.descriptor` would pass the meta type (`type`) of the type of `C`
(`Literal[C]`) as the owner argument to `__get__`, instead of passing
`Literal[C]` directly.

## Test Plan

New test.

crates/red_knot_python_semantic/resources/mdtest/descriptor_protocol.md

@@ -285,6 +285,31 @@ C.descriptor = "something else"
 reveal_type(C.descriptor)  # revealed: Unknown | int
 ```
 
+## `__get__` is called with correct arguments
+
+```py
+from __future__ import annotations
+
+class TailoredForClassObjectAccess:
+    def __get__(self, instance: None, owner: type[C]) -> int:
+        return 1
+
+class TailoredForInstanceAccess:
+    def __get__(self, instance: C, owner: type[C] | None = None) -> str:
+        return "a"
+
+class C:
+    class_object_access: TailoredForClassObjectAccess = TailoredForClassObjectAccess()
+    instance_access: TailoredForInstanceAccess = TailoredForInstanceAccess()
+
+reveal_type(C.class_object_access)  # revealed: int
+reveal_type(C().instance_access)  # revealed: str
+
+# TODO: These should emit a diagnostic
+reveal_type(C().class_object_access)  # revealed: TailoredForClassObjectAccess
+reveal_type(C.instance_access)  # revealed: TailoredForInstanceAccess
+```
+
 ## Descriptors with incorrect `__get__` signature
 
 ```py

crates/red_knot_python_semantic/src/types.rs

@@ -1663,7 +1663,7 @@ impl<'db> Type<'db> {
                 let member = self.static_member(db, name);
 
                 let instance = None;
-                let owner = self.to_meta_type(db);
+                let owner = *self;
 
                 // TODO: Handle `__get__` call errors (see above).
                 member.map_type(|ty| ty.try_call_dunder_get(db, instance, owner).unwrap_or(ty))