Move E2E download uberjar logic into a composite action (#34647)

* Move E2E download uberjar logic into a composite action

* Check out only the last 20 commits

* Always use the correct, last commit in a branch

This helps us avoid the slippery slope in which GitHub creates a new
merge commit, that doesn't exist in the repo, under our feet.

* Adapt the stress-test workflow to use new download action

* Increase the number of commits to search through

* Update .github/actions/e2e-download-uberjar/action.yml

Co-authored-by: Ryan Laurie <30528226+iethree@users.noreply.github.com>

* Log full artifact name

* Correctly download artifact from the current build

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Co-authored-by: Ryan Laurie <30528226+iethree@users.noreply.github.com>