When draining the view builder, we abort ongoing operations using the
view builder's abort source, which may cause them to fail with
abort_requested_exception or raft::request_aborted exceptions.
Since these failures are expected during shutdown, reduce the log level
in add_new_view from 'error' to 'debug' for these specific exceptions
while keeping 'error' level for unexpected failures.
Closesscylladb/scylladb#26297
(cherry picked from commit 6bc41926e2)
Closesscylladb/scylladb#27537
412aa9a19f