Always use _typeshed.Self, where applicable (#6880)

* Always use `_typeshed.Self`, where applicable

* Revert changes to `google-cloud-ndb` (ambiguous)

* Remove empty line added by script

* Revert changes to `stubs/python-dateutil/dateutil/relativedelta.pyi`

* Manually add a few more that the script missed

* Improve `filelock` annotation

Source code here: https://github.com/tox-dev/py-filelock/blob/79ec7b2826e33b982fe83b057f359448b9d966ba/src/filelock/_api.py#L207

* Improve `opentracing/scope` annotation

Source code here: https://github.com/opentracing/opentracing-python/blob/3e1d357a348269ef54d67f761302fab93dbfc0f7/opentracing/scope.py#L71

* Improve `redis/client` stub

Source code here: https://github.com/redis/redis-py/blob/15f315a496c3267c8cbcc6d6d9c6005ea4d4a4d5/redis/client.py#L1217

* Improve `redis/lock` annotation

Source code here: https://github.com/redis/redis-py/blob/15f315a496c3267c8cbcc6d6d9c6005ea4d4a4d5/redis/lock.py#L155

* Improve `requests/models` annotation

Source code here: https://github.com/psf/requests/blob/d718e753834b84018014a23d663369ac27d1ab9c/requests/models.py#L653

stubs/redis/redis/client.pyi

@@ -680,7 +680,7 @@ class Monitor:
     command_re: Pattern[str]
     monitor_re: Pattern[str]
     def __init__(self, connection_pool) -> None: ...
-    def __enter__(self) -> Monitor: ...
+    def __enter__(self: Self) -> Self: ...
     def __exit__(self, *args: Any) -> None: ...
     def next_command(self) -> dict[str, Any]: ...
     def listen(self) -> Iterable[dict[str, Any]]: ...

stubs/redis/redis/lock.pyi

@@ -1,3 +1,4 @@
+from _typeshed import Self
 from types import TracebackType
 from typing import Any, ClassVar, Protocol
 
@@ -25,7 +26,7 @@ class Lock:
         thread_local: bool = ...,
     ) -> None: ...
     def register_scripts(self) -> None: ...
-    def __enter__(self) -> Lock: ...
+    def __enter__(self: Self) -> Self: ...
     def __exit__(
         self, exc_type: type[BaseException] | None, exc_value: BaseException | None, traceback: TracebackType | None
     ) -> bool | None: ...