Merge pull request #42882 from cyx1231st/wip-seastar-cleanup

crimson/common: minor cleanups to futures

Reviewed-by: Samuel Just <sjust@redhat.com>
Reviewed-by: Chunmei Liu <chunmei.liu@intel.com>
Reviewed-by: Xuehan Xu <xxhdx1985126@gmail.com>
Reviewed-by: Radoslaw Zarzynski <rzarzyns@redhat.com>

diff --cc src/crimson/common/interruptible_future.h
Simple merge