mergify fails to merge release-v0.7 PRs with all positive reviews

[ktdreyer]

Describe the bug
Mergify failed to merge a PR that it should have merged. Nathan discovered that Mergify is mis-configured on the release-v0.7 branch.

To Reproduce
Steps to reproduce the behavior:

1. Create a PR
2. Have two reviewers approve it
3. Wait for mergify to merge it
4. 💀 wait forever

Expected behavior
Mergify merges it as soon as the reviewers have approved it

[ktdreyer]

We need to determine if functional-gpu-small-workflow-complete should exist on the release-v0.7 branch:

• If that test should exist on that branch, we should add it to satisfy the rules in .github/mergify.yml.
• If it should not exist on that branch, we should remove it from .github/mergify.yml