Bootstrap chicken and egg issue with siteid

[brendanheywood]

To reproduce:

Easier to map config to files just to see whats going on, but the issue is the same with both redis and with files

            [
                'conditions' => [
                    'name' => 'core/config',
                ],
                'stores' => ['shared_files'],
            ],

Now run this in two tabs:

/var/lib/sitedata# grep -r checkcachewebping *

and run these commands rerunning above between every command:

php admin/cli/purge_caches.php
php admin/cli/cfg.php --component=tool_heartbeat
php admin/cli/cfg.php --component=tool_heartbeat

After the first cfg the caches should still be empty. After the second they should be filled. Prior to the patch the first one fills them in the wrong place, and the second results in two pairs of caches