Creating test dashboard do not properly work

Problem Description

The runbooks script test-dashboards.sh is subject to not working at times. It was noted in a slack convo that if a dashboard is nested underneath a directory, we attempt to create the directory which fails which leads to not being able to create a snapshot. If true, we should rework how we perform testing. We should either:

• Be allowed to create directories underneath the snapshots directory
• Forgoe creating the directory and smush the structure such that we only create the desired dashboard

This failure is creating a hinderance when both testing and reviewing MR's.

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This spawned recently from MR: gitlab-com/runbooks!8681 (comment 2417833113)