crimson/common/smp_helpers: fix reactor_map_seq

crimson/common/smp_helpers: fix reactor_map_seq

Copy f into reactor_map_seq which would be kept alive
due to this method being a coroutine. That way, we can ensure
the lambdas passed to each core that are capturing f by
reference would be safe.
Alternatively, we can also copy f by using it's copy ctor and
pass a copy to each shard:
co_await crimson::submit_to(core, F(f))
However, avoiding the copy is possible here due to the sequential
traversal. Note, seastar's invoke_on_all do copy each callback to
every shard and is running the invocation in parallel.

The above would have fixed f's captures to be invalid and result
in a segfaults on diffrent shards.

Fixes: https://tracker.ceph.com/issues/71457
Signed-off-by: Matan Breizman <mbreizma@redhat.com>