chore(test): replace pointless sleeps in billing quota tests with flush

[gantoine]

Problem

ee/billing/test/test_quota_limiting.py had 7 time.sleep(1) calls scattered before update_all_orgs_billing_quotas(). Each one was a cargo-culted attempt to "wait for ClickHouse ingestion" — but they never did anything useful. _create_event only appends to an in-memory cache; the actual flush to ClickHouse happens inside sync_execute, which already calls flush_persons_and_events() itself in the test environment. The sleeps just burned ~7s of real wall-time per run (plus added flake risk) for no coverage.

Changes

• Replace all 7 time.sleep(1) with an explicit flush_persons_and_events() (the repo's documented visibility mechanism), making the data-availability intent clear instead of timing-dependent.
• Drop the now-unused import time.

No assertions changed; this is purely a wall-time / flake fix.

How did you test this code?

I'm an agent. I ran the affected suite locally:

hogli test ee/billing/test/test_quota_limiting.py

Result: 61 passed; the 2 that "failed" are a pre-existing devbox-only environment mismatch (SITE_URL resolves to the devbox host, so the instance group assertion expects http://localhost:8010). They fail identically on unmodified master, and pass when run with SITE_URL=http://localhost:8010 (full suite green, 63/63). Critically, the current_usage == 109 assertion (99 base + 10 created events) passes, proving the explicit flush makes the events visible exactly as the sleep was meant to.

🤖 Agent context

Autonomy: Fully autonomous

Part of a monorepo test-suite cleanup targeting high CI-wall-time tests. Before changing anything I traced sync_execute (posthog/clickhouse/client/execute.py) and confirmed it calls flush_persons_and_events() in TEST mode, so the sleeps were provably redundant. No skills were required for this one (pure test-timing fix). Tool: Claude Code (Opus 4.8).

Requesting review from: Billing

[greptile-apps]

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