Refactor `Dependant.is_async_gen_callable` property for improved memory usage

```
Samples: 200000 - current=318.4 MB  peak=318.4 MB
Samples: 100000 - current=159.2 MB  peak=159.2 MB
Samples: 50000 - current=79.6 MB  peak=79.6 MB
Samples: 1000 - current=1.6 MB  peak=1.6 MB
Samples: 500 - current=0.8 MB  peak=0.8 MB
```

fastapi/dependencies/models.py

@@ -57,6 +57,7 @@ class Dependant:
     _security_scheme_cache: SecurityBase = field(default=None, init=False, repr=False)
     _security_dependencies_cache: list["Dependant"] = field(default=None, init=False, repr=False)
     _is_gen_callable_cache: bool = field(default=None, init=False, repr=False)
+    _is_async_gen_callable_cache: bool = field(default=None, init=False, repr=False)
 
     @property
     def oauth_scopes(self) -> list[str]:
@@ -145,7 +146,6 @@ class Dependant:
             elif inspect.isclass(_unwrapped_call(self.call)):
                 self._is_gen_callable_cache = False
 
-            # optimization to exit early
             if self._is_gen_callable_cache is not None:
                 return self._is_gen_callable_cache
 
@@ -157,7 +157,6 @@ class Dependant:
             ) or inspect.isgeneratorfunction(_unwrapped_call(dunder_call)):
                 self._is_gen_callable_cache = True
 
-            # optimization to exit early
             if self._is_gen_callable_cache is not None:
                 return self._is_gen_callable_cache
 
@@ -170,34 +169,46 @@ class Dependant:
                 self._is_gen_callable_cache = True
             else:
                 self._is_gen_callable_cache = False
-        
+
         return self._is_gen_callable_cache
 
-    @cached_property
+    @property
     def is_async_gen_callable(self) -> bool:
-        if self.call is None:
-            return False  # pragma: no cover
-        if inspect.isasyncgenfunction(
-            _impartial(self.call)
-        ) or inspect.isasyncgenfunction(_unwrapped_call(self.call)):
-            return True
-        if inspect.isclass(_unwrapped_call(self.call)):
-            return False
-        dunder_call = getattr(_impartial(self.call), "__call__", None)  # noqa: B004
-        if dunder_call is None:
-            return False  # pragma: no cover
-        if inspect.isasyncgenfunction(
-            _impartial(dunder_call)
-        ) or inspect.isasyncgenfunction(_unwrapped_call(dunder_call)):
-            return True
-        dunder_unwrapped_call = getattr(_unwrapped_call(self.call), "__call__", None)  # noqa: B004
-        if dunder_unwrapped_call is None:
-            return False  # pragma: no cover
-        if inspect.isasyncgenfunction(
-            _impartial(dunder_unwrapped_call)
-        ) or inspect.isasyncgenfunction(_unwrapped_call(dunder_unwrapped_call)):
-            return True
-        return False
+        if self._is_async_gen_callable_cache is None:
+            if self.call is None:
+                self._is_async_gen_callable_cache = False  # pragma: no cover
+            elif inspect.isasyncgenfunction(
+                _impartial(self.call)
+            ) or inspect.isasyncgenfunction(_unwrapped_call(self.call)):
+                self._is_async_gen_callable_cache = True
+            elif inspect.isclass(_unwrapped_call(self.call)):
+                self._is_async_gen_callable_cache = False
+
+            if self._is_async_gen_callable_cache is not None:
+                return self._is_async_gen_callable_cache
+
+            dunder_call = getattr(_impartial(self.call), "__call__", None)  # noqa: B004
+            if dunder_call is None:
+                self._is_async_gen_callable_cache = False  # pragma: no cover
+            elif inspect.isasyncgenfunction(
+                _impartial(dunder_call)
+            ) or inspect.isasyncgenfunction(_unwrapped_call(dunder_call)):
+                self._is_async_gen_callable_cache = True
+
+            if self._is_async_gen_callable_cache is not None:
+                return self._is_async_gen_callable_cache
+
+            dunder_unwrapped_call = getattr(_unwrapped_call(self.call), "__call__", None)  # noqa: B004
+            if dunder_unwrapped_call is None:
+                self._is_async_gen_callable_cache = False  # pragma: no cover
+            elif inspect.isasyncgenfunction(
+                _impartial(dunder_unwrapped_call)
+            ) or inspect.isasyncgenfunction(_unwrapped_call(dunder_unwrapped_call)):
+                self._is_async_gen_callable_cache = True
+            else:
+                self._is_async_gen_callable_cache = False
+
+        return self._is_async_gen_callable_cache
 
     @cached_property
     def is_coroutine_callable(self) -> bool: