crimson: bump seastar submodule and adapt to its new future API

crimson: bump seastar submodule and adapt to its new future API

Update src/seastar to ceph-umbrella-25.05.0-1074-gcced0236, which is
scylladb/seastar master (fd71a5b4c7) with the ceph patches reapplied,
and adapt crimson to the future API changes the bump brings in:

  - interruptible_future.h: seastar split its single ready_future_marker into
    set_ready_future_marker and set_from_tuple_ready_future_marker; route
    futurize::from_tuple through the matching markers.
  - thread_pool.h: future_state::set() is now templated and get_value() is
    ref-qualified; pass seastar::internal::monostate{} for the void case and
    move the state before reading its value.

These crimson changes need the new seastar, so they share one commit with the
submodule bump. The build stays at Seastar_API_LEVEL 6 here; the level is
raised in the following commit.

Signed-off-by: Kefu Chai <k.chai@proxmox.com>