bootstrap-install: Added remotion of the crontab(1) of seed_mec user

This remotion prevents the wrong/lack of permissions in seed_mec user's
crontab(1), which prevents the agent to correctly edit its crontab(1).

Signed-off-by: Erik Alexandre Pucci <eap08@c3sl.ufpr.br>
Acked-by: Josiney de Souza <josineys@c3sl.ufpr.br>
Acked-by: Klismann Smoger Mottin <ksm09@inf.ufpr.br>