Add Jepsen tests to CI workflow

[pcholakov]

A long time coming but finally ready to merge - adds a step to run the https://github.com/restatedev/jepsen suite (and specifically, the set-vo and set-mds workloads) against open PRs.

[github-actions]

Test Results

  7 files  ±0    7 suites  ±0   3m 19s ⏱️ -2s
 45 tests ±0   44 ✅ ±0  1 💤 ±0  0 ❌ ±0 
174 runs  ±0  171 ✅ ±0  3 💤 ±0  0 ❌ ±0 

Results for commit 8116cc0. ± Comparison against base commit 622f4b0.

♻️ This comment has been updated with latest results.

[pcholakov]

This is only enabled on the internal docker artifact we attach to the workflow run - same one that gets used by the SDK tests.

[pcholakov]

This test currently runs after docker, just like the SDK tests. At the moment it takes ~3 min but we can tune it to run for shorter or longer. The downside is that there's a single Jepsen workers cluster backing it so we need to run multiple PRs sequentially. As long as there isn't a big backlog of PRs, it shouldn't add any more time to the overall PR checks duration.

[pcholakov]

I expect this will be flaky for a while - I believe this will make it report error but not block PR merging. But, I may be wrong about how this behaves :-)