Copy Tempest stestr timing data for reuse

[kstrenkova]

Currently when running Tempest tests multiple times, it always starts without any information. This patch adds a possibility to reuse timing data from the first Tempest run, so it saves time the next run.

[openshift-ci]

Skipping CI for Draft Pull Request.
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[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kstrenkova
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[openshift-merge-robot]

PR needs rebase.

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[sdatko]

Closing in favor of #316 (preserving the data across multiple job instances, not only within the same environment)