chore: add runAsGroup to backup-job securityContext

What does this MR do?

Adds runAsGroup to the backup-job's secuirtyContext with 1000 as the default value.

Currently there the toolbox helm chart does not set runAsGroup in the pod securityContext. Policy enforcement often has organization rules requiring this to be set to a non-root GID. I had a situation where the policy on a cluster prevented the job pod from being scheduled resulting in backups not being performed.

The original commit adds runAsGroup to the chart values. During the review process, it was pointed out that this chart handles securityContext templating differently than most. At the request of the reviewer, this was changed.

Related issues

N/A

Author checklist

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Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes (!3642 (comment 1821932361))
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• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.