Besides mentioned tarantool#10485 we also fix a similar memleak (updating user)
that introduced by the same commit 5b32bb7 ("alter: Refactor
access_check outside constructors").

Closes tarantool#10485
Part-of tarantool#10211

NO_TEST=covered by existing tests
NO_DOC=bugfix

The issue is we increment `page_count` only on page write. If we fail
for some reason before then page info `min_key` in leaked.

LSAN report for 'vinyl/recovery_quota.test.lua':

```
2024-07-05 13:30:34.605 [478603] main/103/on_shutdown vy_scheduler.c:1668 E> 512/0: failed to compact range (-inf..inf)

=================================================================
==478603==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 4 byte(s) in 1 object(s) allocated from:
    #0 0x5e4ebafcae09 in malloc (/home/shiny/dev/tarantool/build-asan-debug/src/tarantool+0x1244e09) (BuildId: 20c5933d67a3831c4f43f6860379d58d35b81974)
    tarantool#1 0x5e4ebb3f9b69 in vy_key_dup /home/shiny/dev/tarantool/src/box/vy_stmt.c:308:14
    tarantool#2 0x5e4ebb49b615 in vy_page_info_create /home/shiny/dev/tarantool/src/box/vy_run.c:257:23
    tarantool#3 0x5e4ebb48f59f in vy_run_writer_start_page /home/shiny/dev/tarantool/src/box/vy_run.c:2196:6
    tarantool#4 0x5e4ebb48c6b6 in vy_run_writer_append_stmt /home/shiny/dev/tarantool/src/box/vy_run.c:2287:6
    tarantool#5 0x5e4ebb72877f in vy_task_write_run /home/shiny/dev/tarantool/src/box/vy_scheduler.c:1132:8
    tarantool#6 0x5e4ebb73305e in vy_task_compaction_execute /home/shiny/dev/tarantool/src/box/vy_scheduler.c:1485:9
    tarantool#7 0x5e4ebb73e152 in vy_task_f /home/shiny/dev/tarantool/src/box/vy_scheduler.c:1795:6
    tarantool#8 0x5e4ebb01e0b1 in fiber_cxx_invoke(int (*)(__va_list_tag*), __va_list_tag*) /home/shiny/dev/tarantool/src/lib/core/fiber.h:1331:10
    tarantool#9 0x5e4ebc389ee0 in fiber_loop /home/shiny/dev/tarantool/src/lib/core/fiber.c:1182:18
    tarantool#10 0x5e4ebd3e9595 in coro_init /home/shiny/dev/tarantool/third_party/coro/coro.c:108:3

SUMMARY: AddressSanitizer: 4 byte(s) leaked in 1 allocation(s).
```

Closes tarantool#10489
Part-of tarantool#10211

NO_TEST=covered by existing tests
NO_DOC=bugfix

`ffi.C.tnt_iconv_open` returns pointer to `struct iconv`. In this case
`__gc` in metatable is not bound to the object.

Closes tarantool#10487
Part-of tarantool#10211

NO_TEST=covered by existing tests
NO_DOC=bugfix

When replica is deleted from cluster it receives the deletion statement
and then connection to master is closed by master. Since the commit
25aac11 ("box: apply deletion of replica from `_cluster` on the
deleted replica") we kill applier to master on the deletion. Thus the
exit message produced due to EOF on connection to master is never
executed. This message in next in queue after the deletion statement.
As a result the exit message diag with SocketError from applier thread
is not freed.

Closes tarantool#10490
Part-of tarantool#10211

NO_TEST=covered by existing tests
NO_DOC=bugfix