Tidy CABI: remove unnecessary 'release()' before 'wait()'

Author: lukewagner

design/mvp/CanonicalABI.md

@@ -678,7 +678,6 @@ signalled asynchronously via the `async_waiting_tasks` [`asyncio.Condition`].
       self.maybe_start_pending_task()
       v = await self.on_block(awaitable)
       while self.inst.calling_sync_import:
-        Task.current.release()
         await self.async_waiting_tasks.wait()
     return v
 ```

design/mvp/canonical-abi/definitions.py

@@ -452,7 +452,6 @@ async def wait_on(self, awaitable, sync):
       self.maybe_start_pending_task()
       v = await self.on_block(awaitable)
       while self.inst.calling_sync_import:
-        Task.current.release()
         await self.async_waiting_tasks.wait()
     return v