fix(ci): Split instance and volume creation out of the test job

[teor2345]

Motivation

A full sync takes about 6 hours, which is also the GitHub actions time limit.

This is part of ticket #4661, but it only splits off test setup.

We might need this to unblock:

• fix(ci): Ignore lightwalletd hangs for now #4663
• fix(state): Update column family names to match Zebra's database design #4639
• test(grpc): GetMempoolTx and GetMempoolStream test #4537

Designs

Split the existing sync jobs into 2 jobs:

• create instance & volumes
• run test

Solution

Split GCP test jobs into:

• Create instance & create docker volume
• Run test

Related documentation:

• Sort workflow variables into categories and add descriptions
• Document each workflow job and step

Review

These fixes are blocking 3 other PRs, so it's urgent.

Reviewer Checklist

• CI passes
• New setup job runs in checkpoint sync, full sync, and normal tests

[teor2345]

I'm running checkpoint and full syncs here:
https://github.com/ZcashFoundation/zebra/actions/runs/2547182613

We want the setup and test jobs for checkpoint and tip to run successfully.
(It looks like all of the right jobs are in the workflow.)

[conradoplg]

Sync timed out at 80%, I guess it needs #4679 ?

[teor2345]

Sync timed out at 80%, I guess it needs #4679 ?

This isn't the complete implementation of #4661, so it's ok for it to timeout for now

[teor2345]

I checked the cached state disk and regular tests, and they seem to be running the right jobs:

• cached state rebuild - https://github.com/ZcashFoundation/zebra/actions/runs/2547182613
• regular tests - https://github.com/ZcashFoundation/zebra/actions/runs/2547176847

[gustavovalverde]

LGTM!