fix(ci): create a full sync disk to add the cached state inside

[gustavovalverde]

Motivation

Since the first implementation, the resulting disk image after a full sync is not containing the cached state, as it has been an empty disk without the /zebrad-cache dir

Fixes: #4265

Solution

• Mount an extra disk to the full sync test where we're going to save the state
• Standardize this with the checkpoint test

Review

Anyone from @ZcashFoundation/devops-reviewers can review this

Follow Up Work

• refactor(ci): use docker instead of Konlet for GCP deployments in CI #4252

[dconnolly]

I've kicked off https://github.com/ZcashFoundation/zebra/actions/runs/2260540606

[teor2345]

This all looks good, but I'd like @gustavovalverde to be around to test it when it merges.

So I'll open a comment, which you can resolve when you have time to merge and test it.

[teor2345]

Build images failed due to #4234:

Error: buildx failed with: error: failed to solve: failed to fetch oauth token: unexpected status: 401 Unauthorized

https://github.com/ZcashFoundation/zebra/runs/6264577336?check_suite_focus=true#step:9:2180

[gustavovalverde]

Manually merging

[dconnolly]

👍