fix: uuid-ify flow-svc ConfigClient subscription to avoid Pulsar ConsumerBusy on restart (#843)

flow-svc's long-lived ConfigClient was constructed with
subscription=f"{self.id}--config--{id}", where id=params.get("id") is
the deterministic processor id.  On Pulsar the config-response topic
maps to class=response -> Exclusive subscription; when the supervisor
restarts flow-svc within Pulsar's inactive-subscription TTL (minutes),
the previous process's ghost consumer still holds the subscription
and the new process's re-subscribe is rejected with ConsumerBusy,
crash-looping flow-svc.

This is a v2.2 -> v2.3 regression in practice, but not a change in
subscription semantics: the Exclusive mapping for response/notify is
identical between releases.  The regression is that PR #822 split
flow-svc out of config-svc and added this new, long-lived
request/response call site — the new site simply didn't follow the
uuid convention used by the equivalent sites elsewhere
(gateway/config/receiver.py, AsyncProcessor._create_config_client).

Fix: generate a fresh uuid per process instance for the subscription
suffix, matching that convention.

trustgraph-flow/trustgraph/flow/service/service.py

@@ -5,6 +5,7 @@ by coordinating with the config service via pub/sub.
 """
 
 import logging
+import uuid
 
 from trustgraph.schema import Error
 
@@ -83,9 +84,17 @@ class Processor(AsyncProcessor):
             processor=self.id, flow=None, name="config-response",
         )
 
+        # Unique subscription suffix per process instance.  Pulsar's
+        # exclusive subscriptions reject a second consumer on the same
+        # (topic, subscription-name) — so a deterministic name here
+        # collides with its own ghost when the supervisor restarts the
+        # process before Pulsar has timed out the previous session
+        # (ConsumerBusy).  Matches the uuid convention used elsewhere
+        # (gateway/config/receiver.py, AsyncProcessor._create_config_client).
+        config_rr_id = str(uuid.uuid4())
         self.config_client = ConfigClient(
             backend=self.pubsub,
-            subscription=f"{self.id}--config--{id}",
+            subscription=f"{self.id}--config--{config_rr_id}",
             consumer_name=self.id,
             request_topic=config_request_queue,
             request_schema=ConfigRequest,