charts/openrelik make celery process parent, add term grace period for workers

[wajihyassine]

Description of the change

• Add terminationGracePeriodSeconds to all OpenRelik workers to allow more time then the default 30 seconds to gracefully terminate (now to 600 seconds with configurable param to change to higher or lower)
• Add exec in front of celery commands to make them parent process. This way when K8s terminates, Celery can receive the signal and gracefully terminate via a warm shutdown: https://docs.celeryq.dev/en/latest/userguide/workers.html#warm-shutdown
• Add cluster-autoscaler.kubernetes.io/safe-to-evict: "false" to OpenRelik workers as they can have long running tasks and we want to avoid cluster autoscaler from touching these or giving more time when trying to move these as a result of a cluster version upgrade
• Make the grep worker privileged to allow it to operate on mounted disks

Checklist

• Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
• Newly added variables are documented in the values.yaml
• Title of the pull request is descriptive

[hacktobeer]

LGTM with the nit that the plaso worker needs a 2 hour graceperiod at a minimum