Drop `Flume.feed`, it's unused yet causes import cycles..

piker/data/feed.py

@@ -973,9 +973,6 @@ async def open_feed(
                     # assert flume.mkt.fqme == fqme
                     feed.flumes[fqme] = flume
 
-                    # TODO: do we need this?
-                    flume.feed = feed
-
                     # attach and cache shm handles
                     rt_shm = flume.rt_shm
                     assert rt_shm

piker/data/flows.py

@@ -22,9 +22,6 @@ real-time data processing data-structures.
 
 """
 from __future__ import annotations
-from typing import (
-    TYPE_CHECKING,
-)
 
 import tractor
 import pendulum
@@ -38,9 +35,6 @@ from ._sharedmem import (
 )
 from piker.accounting import MktPair
 
-if TYPE_CHECKING:
-    from piker.data.feed import Feed
-
 
 class Flume(Struct):
     '''
@@ -80,10 +74,6 @@ class Flume(Struct):
     izero_rt: int = 0
     throttle_rate: int | None = None
 
-    # TODO: do we need this really if we can pull the `Portal` from
-    # ``tractor``'s internals?
-    feed: Feed|None = None
-
     @property
     def rt_shm(self) -> ShmArray:
 
@@ -156,7 +146,6 @@ class Flume(Struct):
         # will get instead some kind of msg-compat version
         # that it can load.
         msg.pop('stream')
-        msg.pop('feed')
         msg.pop('_rt_shm')
         msg.pop('_hist_shm')