Drop `trio`-exc-catching if tpt-closed covers them

Remove the `trio.ClosedResourceError` and `trio.BrokenResourceError`
handling that should now be subsumed by `TransportClosed` re-raising out
of the `.ipc` stack.

Deats,
- drop CRE and BRE from `._streaming.MsgStream.aclose()/.send()` blocks.
- similarly rm from `._context.open_context_from_portal()`.
- also from `._portal.Portal.cancel_actor()` and drop the
  (now-completed-todo) comment about this exact thing.

Also add comment in `._rpc.try_ship_error_to_remote()` noting the
remaining `trio` catches there are bc the `.ipc` layers *should* be
wrapping them; thus `log.critical()` use is warranted.

(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

tractor/_context.py

@@ -2429,11 +2429,7 @@ async def open_context_from_portal(
             try:
                 # await pause(shield=True)
                 await ctx.cancel()
-            except (
-                trio.BrokenResourceError,
-                trio.ClosedResourceError,
-                TransportClosed,
-            ):
+            except TransportClosed:
                 log.warning(
                     'IPC connection for context is broken?\n'
                     f'task: {ctx.cid}\n'

tractor/_portal.py

@@ -329,18 +329,7 @@ class Portal:
             # if we get here some weird cancellation case happened
             return False
 
-        except (
-            # XXX, should never really get raised unless we aren't
-            # wrapping them in the below type by mistake?
-            #
-            # Leaving the catch here for now until we're very sure
-            # all the cases (for various tpt protos) have indeed been
-            # re-wrapped ;p
-            trio.ClosedResourceError,
-            trio.BrokenResourceError,
-
-            TransportClosed,
-        ) as tpt_err:
+        except TransportClosed as tpt_err:
             ipc_borked_report: str = (
                 f'IPC for actor already closed/broken?\n\n'
                 f'\n'

tractor/_rpc.py

@@ -935,6 +935,11 @@ async def try_ship_error_to_remote(
 
         # XXX NOTE XXX in SC terms this is one of the worst things
         # that can happen and provides for a 2-general's dilemma..
+        #
+        # FURHTER, we should never really have to handle these
+        # lowlevel excs from `trio` since the `Channel.send()` layers
+        # downward should be mostly wrapping such cases in a
+        # tpt-closed; the `.critical()` usage is warranted.
         except (
             trio.ClosedResourceError,
             trio.BrokenResourceError,

tractor/_streaming.py

@@ -410,10 +410,7 @@ class MsgStream(trio.abc.Channel):
             # it).
             with trio.CancelScope(shield=True):
                 await self._ctx.send_stop()
-
         except (
-            trio.BrokenResourceError,
-            trio.ClosedResourceError,
             TransportClosed,
         ) as re:
             # the underlying channel may already have been pulled
@@ -595,8 +592,6 @@ class MsgStream(trio.abc.Channel):
                 ),
             )
         except (
-            trio.ClosedResourceError,
-            trio.BrokenResourceError,
             BrokenPipeError,
             TransportClosed,
         ) as _trans_err: