feat(aci): useMetricDetectorLimit

[leedongwei]

Used by #97953

[malwilley]

const {..., getResponseHeader} = useDetectorsQuery({
  query: 'type:metric'
  limit: 0
}, {
  enabled: !organization.features.includes('workflow-engine-metric-detector-limit') ||
       detectorLimit === UNLIMITED_QUOTA
})

const hits = getResponseHeader()['X-Hits'];
const totalMetricDetectors = hits ? parseInt(hits): 0;

This will get the max number through the header so we don't return every detector in the response data, and limit it to metric detectors. Also skips the request if it's not necessary

[malwilley]

We can also disable this request if there is an unlimited quota

[cursor]

Bug: Hook Misinterprets Header, Bypasses Limits

The hook incorrectly parses non-numeric X-Hits header values, resulting in detectorCount being NaN. This causes hasReachedLimit to always be false and isError to be incorrect, potentially bypassing detector limits. Additionally, the detector query runs unnecessarily when detectorLimit is unlimited, and the hook's early return then misreports isLoading and isError states.