Have mock_uss retry queries with connection reset by peer

[BenjaminPelletier]

Is your feature request related to a problem? Please describe.
mock_uss was observed to cause a test run to fail because a DELETE call to the DSS had its connection reset by peer; see log_messages reported by mock_uss upon the failure to delete the flight:

item_1: [2025-12-17 18:59:25.868 DEBUG monitoring.mock_uss.scd_injection.routes_injection:log:278] [delete_flight/24:13304d0d-b0ec-4ffc-a7c9-d1ae17154020] Acquiring and deleting flight
item_2: [2025-12-17 18:59:25.874 DEBUG monitoring.mock_uss.scd_injection.routes_injection:log:278] [delete_flight/24:13304d0d-b0ec-4ffc-a7c9-d1ae17154020] deleting operational intent c3eedd02-e4c2-41e7-9225-e241f6500fc6 with OVN B.OGW7Gr6fm9cMATw7d1TR-tuIR8Oi-7TOvl.njsXso_ from DSS
item_3: [2025-12-17 18:59:26.241 WARNING monitoring.monitorlib.fetch:query_and_describe:690] query_and_describe attempt 1 from PID 24 to DELETE /dss/v1/operational_intent_references/c3eedd02-e4c2-41e7-9225-e241f6500fc6/B.OGW7Gr6fm9cMATw7d1TR-tuIR8Oi-7TOvl.njsXso_ failed with non-retryable ConnectionError: ('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))
At File "/app/monitoring/monitorlib/clients/scd.py", line 130, in delete_operational_intent_reference
item_4: [2025-12-17 18:59:26.242 DEBUG monitoring.mock_uss.scd_injection.routes_injection:log:278] [delete_flight/24:13304d0d-b0ec-4ffc-a7c9-d1ae17154020] Unexpected response from remote server while deleting operational intent c3eedd02-e4c2-41e7-9225-e241f6500fc6 with OVN B.OGW7Gr6fm9cMATw7d1TR-tuIR8Oi-7TOvl.njsXso_ from DSS for flight 13304d0d-b0ec-4ffc-a7c9-d1ae17154020: deleteOperationalIntentReference from /dss/v1/operational_intent_references/c3eedd02-e4c2-41e7-9225-e241f6500fc6/B.OGW7Gr6fm9cMATw7d1TR-tuIR8Oi-7TOvl.njsXso_ failed 999:

Describe the solution you'd like
Include ConnectionResetError in the set of conditions that indicate a retryable query. With this change, mock_uss would have retried the DELETE operation, that retry hopefully would have succeeded, and the test hopefully would have not have failed due to the failed interaction between mock_uss and the DSS.