The 'restart' option of the init script cannot restart CH if it was not able to shutdown in `shutdown_wait_unfinished` seconds.
```
# sudo /etc/init.d/clickhouse-server restart
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
The process with pid = 14388 is running.
Sent terminate signal to process with pid 14388.
Waiting for server to stop
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
The process with pid = 14388 is running.
Waiting for server to stop
...
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
Waiting for server to stop
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
Waiting for server to stop
...
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
Will terminate forcefully.
Code: 425, e.displayText() = DB::ErrnoException: Cannot send kill signal, errno: 3, strerror: No such process (version 21.1.3.32 (official build))
```
The log:
```
2021.02.08 18:57:23.999226 [ 14388 ] {} <Information> Application: Closed connections. But 3 remain. Tip: To increase wait time add to config: <shutdown_wait_unfinished>60</shutdown_wait_unfinished>
2021.02.08 18:57:24.016684 [ 14388 ] {} <Information> Application: Will shutdown forcefully.
2021.02.08 18:58:28.478835 [ 23658 ] {} <Information> Application: Will watch for the process with pid 23659
2021.02.08 18:58:28.478962 [ 23659 ] {} <Information> Application: Forked a child process to watch
2021.02.08 18:58:28.479067 [ 23659 ] {} <Information> StatusFile: Status file /var/run/clickhouse-server/clickhouse-server.pid already exists - unclean restart. Contents: 14388
2021.02.08 18:58:28.479147 [ 23659 ] {} <Information> SentryWriter: Sending crash reports is disabled
2021.02.08 18:58:28.479183 [ 23659 ] {} <Trace> Pipe: Pipe capacity is 1.00 MiB
2021.02.08 18:58:28.532977 [ 23659 ] {} <Information> : Starting ClickHouse 21.1.3.32 with revision 54445, build id: 63BC1671E8C217170F9B6C6346099FD1F76E784F, PID 23659
2021.02.08 18:58:28.533059 [ 23659 ] {} <Information> Application: starting up
```

if (!group.empty())
        {
            {
                fmt::print("Creating clickhouse group if it does not exist.\n");
                std::string command = fmt::format("groupadd -r {}", group);
                fmt::print(" {}\n", command);
                executeScript(command);
            }
        }
        else
            fmt::print("Will not create clickhouse group");
        if (!user.empty())
        {
            fmt::print("Creating clickhouse user if it does not exist.\n");
            std::string command = group.empty()
                ? fmt::format("useradd -r --shell /bin/false --home-dir /nonexistent --user-group {}", user)
                : fmt::format("useradd -r --shell /bin/false --home-dir /nonexistent -g {} {}", group, user);
            fmt::print(" {}\n", command);
            executeScript(command);
            if (group.empty())
                group = user;
            
            try
            {
                fs::path ulimits_dir = "/etc/security/limits.d";
                fs::path ulimits_file = ulimits_dir / fmt::format("{}.conf", user);
                fmt::print("Will set ulimits for {} user in {}.\n", user, ulimits_file.string());
                std::string ulimits_content = fmt::format(
                    "{0}\tsoft\tnofile\t262144\n"
                    "{0}\thard\tnofile\t262144\n", user);