Ghost meetings on scheduler

We are seeing an increase on the number of meetings that are left in `draft` mode (ghost meetings) and duplicate meetings being created.

Most cases what is happening is that a cloud flow takes a while to finish. PowerApps response times out so the application thinks the cloud flow failed. The user thinks there is an error and tries to book again.
This causes the cloud flow to be executed multiple times, only saving the last entry in our DB and therefore invalidating the other meetings.

Besides moving the architecture to an async creation model, are there other things we can do to mitigate this problem?

No files, tests, or entry points are identified. Start by tracing the scheduler's draft-meeting creation and cloud-flow timeout path, then define a mitigation that prevents duplicate bookings and invalid draft meetings before implementation.

Written by the indexing model from the issue text.