Prevent gRRPC's BackupStatus from canceling pending futures

rzvoncek commented 7 months ago

Fixes #742.

Prior to this patch, I could even reproduce the exception from the issue in the integration tests:

[2024-04-11 13:17:02,362] INFO: Registered backup id grpc_backup_23
[2024-04-11 13:17:02,363] INFO: Recording async backup information.
[2024-04-11 13:17:02,363] ERROR: Exception in callback record_backup_info(<Future cancelled>) at /Users/zvo/github/cassandra-medusa/medusa/service/grpc/server.py:346
handle: <Handle record_backup_info(<Future cancelled>) at /Users/zvo/github/cassandra-medusa/medusa/service/grpc/server.py:346>
Traceback (most recent call last):
  File "/Users/zvo/anaconda3/lib/python3.11/asyncio/events.py", line 80, in _run
    self._context.run(self._callback, *self._args)
  File "/Users/zvo/github/cassandra-medusa/medusa/service/grpc/server.py", line 349, in record_backup_info
    if future.exception():
       ^^^^^^^^^^^^^^^^^^
asyncio.exceptions.CancelledError: Removal of backup requested. Cancelling backup Name: grpc_backup_23 with done state: False