Include git metadata in docker logs and Google Cloud panic reports

[teor2345]

Motivation

Currently,

• Zebra's Docker logs don't show the git commit
• Zebra's Google Cloud and Docker panic reports only show the git commit, passed through an environmental variable.

But we'd like to see the branch name and other detailed git information via vergen.

Tasks

The vergen git metadata is likely being disabled due to git security rules.

The fix is here:
https://github.com/rustyhorde/vergen#notes-about-the-optional-git2-015-dependency

If that doesn't work, we should also check:

• there is a git binary installed in Docker,
• there is a .git directory in Google cloud builds,
• the path to that directory is where vergen or the zebrad build script expect it to be.

We could try changing to the zebra source directory before building.

API Reference

https://docs.rs/vergen/5.1.14/vergen/index.html

[teor2345]

PR #4939 removes the git commit from some Google Cloud objects, so this ticket needs to be done soon.

[teor2345]

This is useful, and we should do it eventually, but it hasn't actually been a problem yet.

[teor2345]

We're doing fine diagnosing bugs without this

[teor2345]

Vergen just added documentation about how to fix this issue in Docker to its readme.