chore: remove labs-owned deploy workflows and scenario/kind/bench machinery

[fcarreiro]

FOUNDATION ONLY

Follow-up to #25213, which retired the runs but deliberately left the machinery. This removes it, plus the deployment workflows that are owned by the labs repo now.

Workflows deleted

• weekly-proving-bench.yml, nightly-spartan-bench.yml, nightly-bench-inclusion-sweep.yml, bench-inclusion-point.yml (its only consumer was the sweep)
• deploy-network.yml, deploy-irm.yml, deploy-staging-public.yml, deploy-staging-internal.yml
• create-devnet.yml, devnet-deploys.yml, create-release-branch.yml
• ensure-funded-environment.yml, ensure-funded-environments.yml, network-healthcheck.yml
• .github/actions/network-teardown/ (only used by nightly-spartan-bench) and .claude/claudebox/deploy-investigation.md (only dispatched by deploy-network)

test-network-scenarios.yml was already deleted in #25213.

Machinery removed

• ci3.yml: the label-triggered ci-network-bench and ci-network-kind jobs (the &ci_benchmark_* anchors they consumed are inlined back into the ci job).
• ci.sh: all network-* verbs (scenarios/deploy/tests/bench/proving-bench/block-capacity-bench/bench-10tps/inclusion-sweep/teardown/tests-kind) and the gh-spartan-* benchmark download aliases. deploy-rollup-upgrade stays.
• bootstrap.sh: the whole ci-network-* mode block. ci-bench (the m6a.metal benchmark box) stays.
• spartan/bootstrap.sh: scenario test sets and runners, the network/proving/block-capacity/inclusion bench functions and GCS uploader, and the kind / test-kind-upgrade-rollup / network_deploy / network_teardown / wait_for_l2_block wrappers.
• ci3/run_test_cmd: the scenario-only Slack fail notification (SCENARIO_TESTS / #alerts-next-scenario).
• spartan: benchmarks/README.md, quickstart.md, scripts/test_kind.sh, scripts/kind-config.yaml, scripts/patch_dns.sh, scripts/wait_for_l2_block.sh, scripts/bench_10tps/, and the scenario/kind/bench env files (tps-scenario, next-scenario, scenario.local, kind-minimal, kind-provers, prove-n-tps-fake, prove-n-tps-real, bench-10tps, bench-inclusion-sweep, block-capacity) with their .gitignore whitelist lines.

Deliberately kept

• spartan/scripts/network_deploy.sh, network_teardown.sh, funding scripts — the labs repo's workflows are the consumers of record for this tooling.
• yarn-project/end-to-end/src/spartan/ test sources and the aztec-chaos-scenarios chart they drive.
• extract_proving_metrics.ts (used by the network-logs agent) and metrics/RPC deploy workflows (metrics-deploy.yml, deploy-rpc.yml).

Stale doc pointers left for a separate docs pass: yarn-project/BRANCHING.md (create-release-branch), ci3/dashboard deploy-lag workflow list, and the kind references in end-to-end/src/spartan/DEVELOP.md.

Validation: YAML parse on all remaining workflows, bash -n on every edited shell script, and a repo-wide grep sweep for the removed verbs/modes/scripts/envs (remaining hits are the doc pointers listed above and comments in the kept e2e tests).