ci: add e2e bulk kill test

[ashtonG]

Ticket

ET-674

Description

This adds a test to the e2e test suite that tests the bulk experiment kill flow.

Test Plan

e2e tests should continue to pass, no other testing required.

Checklist

• [x] Changes have been manually QA'd
• [x] New features have been approved by the corresponding PM
• [x] User-facing API changes have the "User-facing API Change" label
• [x] Release notes have been added as a separate file under docs/release-notes/ See Release Note for details.
• [x] Licenses have been included for new code which was copied and/or modified from any external code