[bug]: parallel call http endpoint `/actors/kqp_proxy?force_shutdown=all` with the number of sessions > 1 will kill the database

[KirillKurdyukov]

YDB must have more than one active session

Thread 25 "ydbd.User" received signal SIGFPE, Arithmetic exception.
[Switching to Thread 0x7f8e698bd700 (LWP 106)]
0x000055e9d0711163 in NKikimr::NKqp::TLocalSessionsRegistry::PickSessionToShutdown (this=0x4432ffdba890,
    force=<optimized out>, minReasonableToKick=minReasonableToKick@entry=0)
    at /home/pixcc/ydbwork/ydb/ydb/core/kqp/proxy_service/kqp_proxy_service_impl.h:283
283 /home/pixcc/ydbwork/ydb/ydb/core/kqp/proxy_service/kqp_proxy_service_impl.h: No such file or directory.
(gdb) where
#0  0x000055e9d0711163 in NKikimr::NKqp::TLocalSessionsRegistry::PickSessionToShutdown (
    this=0x4432ffdba890, force=<optimized out>, minReasonableToKick=minReasonableToKick@entry=0)
    at /home/pixcc/ydbwork/ydb/ydb/core/kqp/proxy_service/kqp_proxy_service_impl.h:283
#1  0x000055e9d07045f0 in NKikimr::NKqp::(anonymous namespace)::TKqpProxyService::ProcessMonShutdownQueue (
    this=0x4432fcc00000, wantsToShutdown=2)
    at /home/pixcc/ydbwork/ydb/ydb/core/kqp/proxy_service/kqp_proxy_service.cpp:1113
#2  NKikimr::NKqp::(anonymous namespace)::TKqpProxyService::Handle (this=0x4432fcc00000, ev=...)
    at /home/pixcc/ydbwork/ydb/ydb/core/kqp/proxy_service/kqp_proxy_service.cpp:1136
#3  NKikimr::NKqp::(anonymous namespace)::TKqpProxyService::MainState (this=0x4432fcc00000, ev=...)
    at /home/pixcc/ydbwork/ydb/ydb/core/kqp/proxy_service/kqp_proxy_service.cpp:1298
#4  0x000055e9c071fe35 in NActors::TGenericExecutorThread::Execute<NActors::TMailboxTable::THTSwapMailbox> (
    this=this@entry=0x4432fc796480, mailbox=0x4432f72804c0, hint=hint@entry=4115,
    isTailExecution=<optimized out>)
    at /home/pixcc/ydbwork/ydb/ydb/library/actors/core/executor_thread.cpp:250
#5  0x000055e9c0717c62 in NActors::TGenericExecutorThread::ProcessExecutorPool(NActors::IExecutorPool*)::$_0::operator()(unsigned int, bool) const (this=this@entry=0x7f8e69888048, activation=activation@entry=4115,
    isTailExecution=false) at /home/pixcc/ydbwork/ydb/ydb/library/actors/core/executor_thread.cpp:435
#6  0x000055e9c07175f1 in NActors::TGenericExecutorThread::ProcessExecutorPool (
    this=this@entry=0x4432fc796480, pool=<optimized out>)
    at /home/pixcc/ydbwork/ydb/ydb/library/actors/core/executor_thread.cpp:488
#7  0x000055e9c0718486 in NActors::TExecutorThread::ThreadProc (this=0x4432fc796480)
    at /home/pixcc/ydbwork/ydb/ydb/library/actors/core/executor_thread.cpp:517
#8  0x000055e9bf9b7b87 in (anonymous namespace)::TPosixThread::ThreadProxy (arg=0x4432ff5a6e80)
    at /home/pixcc/ydbwork/ydb/util/system/thread.cpp:244
#9  0x00007f8e754a0609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#10 0x00007f8e753c0353 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95