fix buildkite checking out mantis-automation

[nrdxp]

Description

Buildkite is erroneously checking out mantis-automation somehow do to some strange hook bug.

Proposed Solution

A clean checkout looks like it is required to keep the repo's separate for whatever reason. Also @AurelienRichez's fix to add a - wait statement also was compounding the issue, since this caused the first step to not run at all, and skip directly to mantis automation step.

[dzajkowski]

I think this needs to be parked until we figure out how to run these tests in a less disruptive way.