Restart EOTK once a week

Adds a cronjob to restart EOTK once a week to avoid any existing issues with long-lived Onion Services.

Uses the instance index as the day of the week in the cronjob.

See discussion at https://gitlab.torproject.org/tpo/onion-services/onion-support/-/issues/192

I haven't tested it beyond the syntax as currently I don't have access to a proper testing environment.

I'm also very new into Terraform.

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