fix: allow workspaces to be attempted to be deleted when experiments had existed historically [CM-412]

[corban-beaird]

Ticket

CM-412

Description

A bug in the webUI was found where workspaces couldn't be deleted if there had ever been an experiment present in the workspace at any point in time. This removes the frontend check to disable the delete action in the action dropdown & adds logic into the API to perform the experiment present check.

Test Plan

• CI passes

Checklist

• [ ] Changes have been manually QA'd
• [ ] New features have been approved by the corresponding PM
• [ ] User-facing API changes have the "User-facing API Change" label
• [ ] Release notes have been added as a separate file under docs/release-notes/ See Release Note for details.
• [ ] Licenses have been included for new code which was copied and/or modified from any external code