## What changed?
Run cassandra with smaller heap (2GB) in CI. Default (on standard GHA
workers) comes out to 4GB, so this is 1/2 of what it was before.
## Why?
Try to reduce CI flakiness.
## What changed?
<!-- Describe what has changed in this PR -->
Github workflow to run tests.
I couldn't add tests on `windows-latest` nor `macos-latest` at this moment.
In Windows, there are issues with filepaths in the archiver (eg: `file:///home/` vs `file:///c:\\`, note that in Windows, it needs a forward slash before the actual path `c:\\`, but it messes up with the actual path)
In MacOS, it doesn't have Docker installed by default.
Also, in both Windows and MacOS, some TLS related unit tests are failing.
## Why?
<!-- Tell your future self why have you made these changes -->
Replace buildkite.
## How did you test it?
<!-- How have you verified this change? Tested locally? Added a unit test? Checked in staging env? -->
Ran in my fork: https://github.com/rodrigozhou/temporal/actions/runs/7401242980
## Potential risks
<!-- Assuming the worst case, what can be broken when deploying this change to production? -->
No.
## Is hotfix candidate?
<!-- Is this PR a hotfix candidate or does it require a notification to be sent to the broader community? (Yes/No) -->
No.
