NBK-164: streamline and instrument DDSQL async polling

[nmuldavin]

Linear

NBK-164 — https://linear.app/datadoghq/issue/NBK-164/pup-remove-the-redundant-ddsql-poll-sleep-and-instrument-the-async

Outcome

DDSQL async queries poll without redundant success-path sleeps until AQA returns a terminal state, while individual HTTP and rate-limit waits remain bounded and long waits are reported without contaminating command output.

Scope

• Share polling semantics across public v2 table/time-series execution and the existing findings-analyze path.
• Bound submissions to 60 seconds and fetches to 15 seconds without imposing a client-wide query deadline.
• Honor Retry-After and exponentially retry 429s within a 20-second total retry window, below AOP's 30-second polling-liveness timeout.
• Emit staged progress only on interactive stdout/stderr; piped and agent-mode output remains quiet.
• Non-goal: add a user-configurable --timeout flag.

This was developed on top of #785 (NBK-161) and is rebased onto main after that dependency merged.

Acceptance

• Successful polls have no client-side sleep.
• There is no client-wide elapsed-time deadline; AQA terminal states or caller cancellation end polling.
• Initial and fetch requests have independent HTTP timeouts.
• Initial submissions and fetches retry 429 / Retry-After with exponential backoff inside a 20-second total retry window.
• Fetch HTTP, rate-limit, and response-state failures include the query ID when available.
• Interactive progress starts around 10 seconds and escalates around 30 seconds with narrowing / LIMIT guidance.
• Progress is stderr-only and suppressed for pipes and agent mode, preserving JSON stdout.
• Table, time-series, and findings-analyze use the shared polling implementation.

Validation

• cargo test commands::ddsql::tests --no-fail-fast — 49 DDSQL tests passed, including no-success-sleep, no overall deadline, initial/fetch 429, request timeout, and query-ID diagnostics.
• cargo clippy --all-targets -- -D warnings — passed.
• cargo test --no-fail-fast -- --test-threads=1 — 1,914 tests passed.
• cargo fmt --check — passed.
• git diff --check — passed.
• Fresh-context final review — no blocker, high, or medium findings.
• Draft CI — all five real checks passed, including Linux/macOS/Windows cross-compilation and WASM.

Not run / automation gaps

• cargo audit — unavailable because cargo-audit is not installed; this change adds no dependencies.
• Cross-platform compilation and live long-running DDSQL verification are left to CI / manual verification.

Material deviations and decisions

• Removed the previously implemented two-minute client deadline after confirming AQA has server-side execution and abandoned-client controls.
• Kept request and rate-limit waits bounded so network failures cannot hang one HTTP operation indefinitely.
• Kept --timeout out of scope.

Remaining work or conditions

• Human approval is required before marking the PR ready for review.

[nmuldavin]

Closing this draft because NBK-164 was re-scoped and this implementation no longer matches its requirements. The issue remains active and will be reimplemented separately.