chore(detectors): Update experimental N+1 API detector to use rollout flag

[roggenkemper]

adds flag so we can roll out experimental n+1 api call detector.

[codecov]

✅ All tests passed

[cvxluo]

just curious, is the n_plus_one_api_calls_dectector in experiments/ going to be deleted in favor of the other one?

[roggenkemper]

eventually - right now we need to keep it because we want to run the experimental detector for any org with the flag, but keep the legacy behavior for everyone else. once we fully move people over, we can replace the old file with this one

[seer-by-sentry]

Potential bug: The feature flag organizations:experimental-n-plus-one-api-detector-rollout is used but not registered, causing it to always evaluate to False. This prevents the experimental detector from ever running.

• Description: The feature flag organizations:experimental-n-plus-one-api-detector-rollout is used to control the rollout of the NPlusOneAPICallsExperimentalDetector. However, this flag is never registered in any configuration file, such as src/sentry/features/temporary.py. The feature management system defaults unregistered flags to False. As a result, the condition features.has("organizations:experimental-n-plus-one-api-detector-rollout", ...) will always be false, preventing the experimental detector from ever being executed. Conversely, the stable detector will always run, defeating the purpose of the gradual rollout mechanism introduced in this change.

• Suggested fix: Register the feature flag organizations:experimental-n-plus-one-api-detector-rollout in src/sentry/features/temporary.py, similar to how other experimental detector flags like organizations:experimental-mn-plus-one-detector-rollout are registered. This will allow the flag to be enabled for organizations, enabling the experimental detector as intended.
  _{severity: 0.7, confidence: 0.95}

_{Did we get this right? 👍 / 👎 to inform future reviews.}