Rerun e2e tests in CI due to flakyness (#503)

## Summary

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Include a short paragraph of the changes introduced in this PR.
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The e2e tests fail all of the time in CI due to unpredicable compute
time. This PR uses `pytest-rerunfailures` to rerun failing tests up to 3
times.

---

- [x] "I certify that all code in this PR is my own, except as noted
below."

## Use of AI

- [ ] Includes AI-assisted code completion
- [ ] Includes code generated by an AI application
- [ ] Includes AI-generated tests (NOTE: AI written tests should have a
docstring that includes `## WRITTEN BY AI ##`)

Author: sjmonson

.github/workflows/testing.yml

@@ -74,4 +74,5 @@ jobs:
         with:
           python-version: ${{ inputs.python }}
           tox-env: test-e2e
-          tox-args: ${{ inputs.args }}
+          # Rerun e2e tests due to flakyness in CI
+          tox-args: --reruns=3 ${{ inputs.args }}