Fix 'flaky' tests.

[better0fdead]

I've made a list of 'flaky' tests, using avaliable run logs :

flaky tests	test	error
1	test_setup
2	test_setup_bootstrap_vshard	Failed to bootstrap vshard: [string "local function func(...) local cartridge = re..."]:1: No remotes with role "vshard-router" available
3	custom_admin_running_instances	Failed downloading http://rocks.tarantool.org/checks-3.1.0-1.all.rock
4	test_default_application	Failed to bootstrap vshard: [string "local function func(...) local cartridge = re..."]:1: No remotes with role "vshard-router" available
5	test_start_with_timeout	Application dir does not contain ".rocks" directory. Make sure you ran "cartridge build" before running "cartridge start"
6	test_join	Failed to join instances: Failed to edit topology: [string "local function func(...) local cartridge = re..."]:1: "localhost:3304": Replication setup failed, instance orphaned
7	e2e
8	project_with_topology_and_vshard	Failed to bootstrap vshard: [string "local function func(...) local ' 'cartridge = re..."]:1: No remotes with role "vshard-router" available\n')

What's needed:

• to understand why
• create and implement solution