Migrate old flaky test tickets to github

[robrap]

A/C:

• List of unresolved flaky tests in Jira is empty: https://2u-internal.atlassian.net/issues/?filter=10600 (resolution is EMPTY AND labels = flaky_test ORDER BY created DESC) -- 21 here as of 2024-10-11.
• GitHub issues are discoverable, e.g. via a label: flaky-test
• Flaky Test Process is fully updated to refer to the GitHub process

[timmc-edx]

I think I'm done migrating old issues -- the only ones remaining in CR are in ecommerce or edx-e2e-tests, not edx-platform. There are also some LEARNER tickets but they don't appear to be relevant to this flaky test process.

[timmc-edx]

I went through a broader set of tickets and established that everything has been either moved or wasn't relevant (such as individually deleted bokchoy tests).