Context

Cloning DET from master results in unexpected CI failures that are quite difficult to diagnose. E.g., DRIVERS-3550 and DRIVERS-355.

Definition of done

Add drivers-evergreen-tools as a git submodule pinned to a commit, and update setup-system.sh to source $DRIVERS_TOOLS from the submodule rather than an unpinned git clone of master. Configure dependabot to open bump PRs, so DET-introduced regressions surface in dependabot PR instead of breaking unrelated driver PRs.

Note: DET is used as a runtime working dir, so confirm the submodule tolerates the runtime artifacts written into $DRIVERS_TOOLS. If this doesn't work, we can pin a SHA file for the dependabot bump, instead of using git submodules.

Pitfalls

A pinned DET means new-server support requires an explicit bump. We'll set the bump cadence in dependabot.yml (e.g., daily) and allow on-demand bumps when testing a new server version.