Third-party stubs: fix several fictitious type aliases

[AlexWaygood]

Fixes #7954

I also did some driveby TypeAlias fixes.

[AlexWaygood]

Not sure why stubtest is failing to import google-cloud-ndb. Seems like it was able to import it just fine last night: https://github.com/python/typeshed/runs/6602180879?check_suite_focus=true

[AlexWaygood]

For some reason, it looks like stubtest for this PR is installing a different version of protobuf than the one it did for the daily test last night.

---

Last night
protobuf==3.20.1 was installed for testing google-cloud-ndb

This PR
protobuf==4.21.0 is being installed for testing google-cloud-ndb

---

I've no idea if that's what's causing the CI failure here, or why a different version of protobuf is being installed now.

[AlexWaygood]

For some reason, it looks like stubtest for this PR is installing a different version of protobuf than the one it did for the daily test last night.

Last night protobuf==3.20.1 was installed for testing google-cloud-ndb

This PR protobuf==4.21.0 is being installed for testing google-cloud-ndb

I've no idea if that's what's causing the CI failure here, or why a different version of protobuf is being installed now.

Manually pinning the version of protobuf that stubtest installs for google-cloud-ndb seems to have fixed it, so I guess this was the problem.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[JelleZijlstra]

Note that protobuf 4.21.0 was just released yesterday: https://pypi.org/project/protobuf/#history

[AlexWaygood]

Note that protobuf 4.21.0 was just released yesterday: https://pypi.org/project/protobuf/#history

Ahh, makes sense. I was searching through the google-cloud-ndb source code for changes, and couldn't see anything.