feat: add support for destroy_scheduled_duration

[chrisw-tracer]

We had a requirement to override the default 24 hour deletion schedule period. I know this default is changing to 30 days next year but thought this might be useful to others in the mean time.

[google-cla]

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[chrisw-tracer]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

I've completed the CLA

[chrisw-tracer]

@apeabody any feedback on this PR?

[apeabody]

Thanks for the contribution @chrisw-tracer!

[apeabody]

/gcbrun

[apeabody]

/gcbrun