change(release): Enable all user features in the experimental build

[teor2345]

Motivation

We want to be able to point users to an experimental build for all new user features, not just one or two features we've been focused on recently. This makes using those features easier for users, because they don't have to build Zebra themselves.

It also makes our documentation simpler, because we can just say "use the latest-experimental image", rather than explaining which features are in it.

Suggested Solution:

First PR:

• Add an experimental feature to zebrad that just activates default-release-binaries
• Admin: Set the RUST_EXPERIMENTAL_FEATURES GitHub Actions variable to experimental

Second PR:

• Add all user features to the experimental feature: elasticsearch, journald, prometheus, filter-reload, shielded-scan
• Add a config test for the experimental feature (as well as getblockchain-rpcs and shielded-scan), and add a config with all the experimental features enabled

Optional

If the Test all job is slow:

Not needed any more - job is fast

• Split it into an experimental job and a default features job
  

  zebra/.github/workflows/ci-unit-tests-docker.yml

  Lines 122 to 125 in afbe807

  	# Currently GitHub doesn't allow empty variables
  	if [[ -n "${{ vars.RUST_EXPERIMENTAL_FEATURES }}" && "${{ vars.RUST_EXPERIMENTAL_FEATURES }}" != " " ]]; then
  	docker run -e NETWORK --name zebrad-tests-experimental --tty ${{ vars.GAR_BASE }}/${{ vars.CI_IMAGE_NAME }}@${{ needs.build.outputs.image_digest }} cargo test --locked --release --features "${{ env.EXPERIMENTAL_FEATURES }} " --workspace -- --include-ignored
  	fi

• Consider building an experimental image so that we get build caching for that image
• Admin: Add branch protection rules for new jobs

Specifications

No response

Complex Code or Requirements

We don't want to make CI fail when an admin changes the settings, so it's better to split this ticket into 2 PRs.

Testing

Make sure the tests are actually running in CI.

Related Work

No response

[teor2345]

This is blocked by #7891 because we want the new features to appear in the new tags, after the breaking change.

[teor2345]

I've updated this ticket, it looks like we'll need an admin for parts of it, so let's check when @gustavovalverde is around.

[mpguerra]

@gustavovalverde I'm unscheduling this one because there are more pressing things this sprint and I'm a bit lost with this one... Is there anything left to do here?

[arya2]

Is there anything left to do here?

The experimental build was added to CI in #8175 and is testing every PR update: https://github.com/ZcashFoundation/zebra/actions/runs/7997001572/job/21840879753#step:5:105

Some tests fail with the elasticsearch feature (see #8175 (comment)), so it was omitted for now.

We may want an issue for fixing those test failures and adding it to the experimental build, or for adding the internal-miner feature to the experimental build when it's restored.

[mpguerra]

Going to close this as the original scope was done. We should open follow up issues if we want to add any new optional features, such as elasticsearch or internal-miner to the experimental build