vm-img: wait longer that the VM boots

Currently, NEO-STRESS often fails because it is assigned
on the same test node as other test suites that:
- overload the test node;
- are often triggered at the same time.

component/vm-img/debian.cfg

@@ -18,6 +18,7 @@ recipe = slapos.recipe.build:vm.run
 environment = vm-run-environment
 vm = ${vm-debian:location}
 dist = ${vm-debian:dists}
+wait-ssh = 100
 
 [vm-debian]
 recipe = slapos.recipe.build:vm.install-debian