acceptance: extend cmd/lakebox tests to cover write-path commands

[akshaysingla-db]

Summary

Second batch of lakebox acceptance tests, following #5474. Covers 14 leaf scenarios on the write/connection-path commands and JSON output shapes that weren't in the first batch.

Test	What it locks down
list/json	-o json shape (no FQDN field, gatewayHost present, idleTimeout serialized as Duration string)
status/running	Happy-path text output with all rendered fields
status/json	JSON shape — verifies the FQDN-removal in #5460 didn't get reverted
ssh-key/list/with-entries	Multi-row table including unnamed key falling back to (unset)
ssh-key/delete/success	DELETE wire route + confirmation message
delete/success	Happy path with --auto-approve to bypass the prompt
delete/not-found	404 → friendly no lakebox named X (the consistency fix from #5460)
delete/no-tty-no-auto-approve	Non-interactive context fast-fails pointing at the --auto-approve flag
default/set	Set default → confirmation message
default/not-found	404 → friendly error (same message as delete)
start/already-running	API returns Running → CLI short-circuits with "Already running X" (skips waitForRunning)
stop/success	Happy path with refreshed status
config/update-name	PATCH wire route + post-update output rendering
create/with-name	POST wire route + stdout ID + default-set side effect

Two test-infrastructure additions

1. acceptance/cmd/lakebox/script.prepare sets HOME=$TEST_TMP_DIR so each test's ~/.databricks/lakebox.json is isolated. Without this, parallel lakebox tests race each other writing to the shared HOME-rooted state file and one read sees the other's half-written content. Auth is unaffected — the framework passes DATABRICKS_HOST / DATABRICKS_TOKEN explicitly via env, so the CLI doesn't fall back to ~/.databrickscfg.

2. EnvMatrix.DATABRICKS_BUNDLE_ENGINE = [] in the parent test.toml overrides the root matrix to skip the per-engine variants. Lakebox is engine-independent and running both variants in parallel was the original symptom of the HOME race.

Two of the ssh-key tests also pin the test key hash via a high-priority [[Repls]] entry so the framework's default 3+-digit-run → [NUMID] regex doesn't shred it mid-hash.

Test plan

• go test ./acceptance -run TestAccept/cmd/lakebox — all 20 tests pass (6 from acceptance: add cmd/lakebox tests #5474 + 14 new)
• ./task lint clean
• Re-running with -update and then without is idempotent (no drift)

Still out of scope

• register — generates and reads real SSH keys via ssh-keygen; needs a heavier fixture / process stub
• ssh — execvs into ssh; not testable through this framework

This pull request and its description were written by Isaac.

[github-actions]

Waiting for approval

Could not determine reviewers from git history.
Round-robin suggestion: @anton-107

Eligible reviewers: @andrewnester, @anton-107, @denik, @pietern, @renaudhartert-db, @shreyas-goenka, @simonfaltum

_{Suggestions based on git history. See OWNERS for ownership rules.}