feat(webvitals): Check if ttfb exists to determine proper no data state (#59912)

Check if ttfb exists to determine proper no data state

Author: edwardgou-sentry

static/app/views/performance/browser/webVitals/utils/getWebVitalValues.tsx

@@ -17,8 +17,7 @@ export function getWebVitalsFromTableData(data: TableDataRow) {
   const hasFcp = hasWebVital(data, 'fcp');
   const hasCls = hasWebVital(data, 'cls');
   const hasFid = hasWebVital(data, 'fid');
-  // TODO: waiting for backend to allowlist ttfb
-  const hasTtfb = true;
+  const hasTtfb = hasWebVital(data, 'ttfb');
 
   return {
     lcp: hasLcp ? getWebVital(data, 'lcp') : null,

static/app/views/performance/browser/webVitals/utils/useProjectWebVitalsQuery.tsx

@@ -30,6 +30,7 @@ export const useProjectWebVitalsQuery = ({transaction, tag, dataset}: Props = {}
         'count_web_vitals(measurements.fcp, any)',
         'count_web_vitals(measurements.cls, any)',
         'count_web_vitals(measurements.fid, any)',
+        'count_web_vitals(measurements.ttfb, any)',
         'count()',
         'failure_count()',
         'p95(transaction.duration)',