Since commit 509f2af8db, gate_closed_exception can be triggered for ongoing split during shutdown. The commit is correct, but it causes split failure on shutdown to log an error, which causes CI instability. Previously, aborted_exception would be triggered instead which is logged as warning. Let's do the same.
Fixes https://scylladb.atlassian.net/browse/SCYLLADB-951.
Fixes https://github.com/scylladb/scylladb/issues/24850.
Only 2026.1 is affected.
Closesscylladb/scylladb#29032
* github.com:scylladb/scylladb:
replica: Demote log level on split failure during shutdown
service: Demote log level on split failure during shutdown
(cherry picked from commit ae17596c2a)
Closesscylladb/scylladb#29115
f2111c011f