Fix possible SSH protocol (due to hang in replxx)

Server logs:

    2025.05.22 10:42:17.241809 [ 564780 ] {} <Trace> SSHHandlerFactory: TCP Request. Address: [::ffff:178.85.148.107]:53044
    ...
    2025.05.22 10:42:17.436561 [ 281521 ] {} <Debug> LOCAL-Session-7596a9ec-e89e-4f7b-ab48-1591f7cd12e1: Creating session context with user_id: 3943f762-da1c-9f93-c9f4-049dcfe9f0b8
    ...

Stack trace for `LocalServerPty`:

    :) select arrayStringConcat(arrayMap(x -> concat(addressToLine(x), '::', demangle(addressToSymbol(x))), trace), '\n') AS sym, * from system.stack_trace where thread_id = 281521 settings allow_introspection_functions=1

    sym:         /usr/bin/clickhouse::DB::(anonymous namespace)::signalHandler(int, siginfo_t*, void*)
    /usr/bin/clickhouse::replxx::Terminal::wait_for_input(long)
    /usr/bin/clickhouse::replxx::Replxx::ReplxxImpl::read_char(replxx::Replxx::ReplxxImpl::HINT_ACTION)
    /usr/bin/clickhouse::replxx::Replxx::ReplxxImpl::input(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&)
    /usr/bin/clickhouse::DB::ReplxxLineReader::readOneLine(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&)
    /usr/bin/clickhouse::DB::LineReader::readLine(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&)
    /usr/bin/clickhouse::DB::ClientBase::runInteractive()

And let's see what it polls:

    root@ip-172-31-3-23:/home/ubuntu# strace -p 281521
    strace: Process 281521 attached
    pselect6(177, [172], NULL, NULL, NULL, NULL

Only one fd, likely due to nfds is too low.

Refs: ClickHouse/replxx#29
Fixes: ClickHouse#80684

Author: azat