db::hints::manager::end_point_hints_manager::stop(): log the last exception instead of forwarding it
db::hints::manager::end_point_hints_manager::stop(): log the last exception instead of forwarding it

Returning a future with an exception from end_point_manager::stop()
is practically useless because the best the caller can do is to log
it and continue as if it didn't happen because it has other things
to shut down.

Therefore in order to simplify the caller we will log the exception
if it happens and will always return a non-exceptional future.

Signed-off-by: Vlad Zolotarov <976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>

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