test: flaky box/access.test.lua test

[avtikhon]

Tarantool version:
Tarantool 2.6.0-136-g2711797be
Target: Darwin-x86_64-RelWithDebInfo
Build options: cmake . -DCMAKE_INSTALL_PREFIX=/Users/tntmac03.tarantool.i/builds/6KMaH8fQ/0/tarantool/tarantool/static-build/tarantool-prefix -DENABLE_BACKTRACE=TRUE
Compiler: /Library/Developer/CommandLineTools/usr/bin/cc /Library/Developer/CommandLineTools/usr/bin/c++
C_FLAGS: -Wno-unknown-pragmas -fexceptions -funwind-tables -fno-omit-frame-pointer -fno-stack-protector -fno-common -msse2 -std=c11 -Wall -Wextra -Wno-strict-aliasing -Wno-char-subscripts -Wno-gnu-alignof-expression -Werror
CXX_FLAGS: -Wno-unknown-pragmas -fexceptions -funwind-tables -fno-omit-frame-pointer -fno-stack-protector -fno-common -msse2 -std=c++11 -Wall -Wextra -Wno-strict-aliasing -Wno-char-subscripts -Wno-invalid-offsetof -Wno-gnu-alignof-expression -Werror

OS version:
OSX 15

Bug description:
https://gitlab.com/tarantool/tarantool/-/jobs/770859510#L484

artifacts.zip

Checksum of results file consists of the changing data:

results file checksum: b713f8a0acf759fd13968fc744034d0b

[048] --- box/access.result	Fri Oct  2 16:25:10 2020
[048] +++ box/access.reject	Sat Oct  3 05:16:46 2020
[048] @@ -50,13 +50,26 @@
[048]  -- is granted access to 'su'
[048]  session.su('test')
[048]  ---
[048] +- error: Session access to universe '' is denied for user 'test'
[048]  ...
[048]  -- you can't create spaces unless you have a write access on
[048]  -- system space _space
[048]  -- in future we may  introduce a separate privilege
[048]  box.schema.space.create('test')
[048]  ---
[048] -- error: Write access to space '_schema' is denied for user 'test'
[048] +- engine: memtx
[048] +  before_replace: 'function: 0x010316bc28'
[048] +  field_count: 0
[048] +  is_sync: false
[048] +  ck_constraint: []
[048] +  on_replace: 'function: 0x01030a3c10'
[048] +  temporary: false
[048] +  index: []
[048] +  is_local: false
[048] +  enabled: false
[048] +  name: test
[048] +  id: 522
[048] +- created
[048]  ...
[048]  -- su() goes through because called from admin
[048]  -- console, and it has no access checks

Steps to reproduce:

Optional (but very desirable):

• coredump
• backtrace
• netstat