ci: reduced Sentry frequency on CircleCI develop (#27912)

## **Description**

Cut in half Sentry frequency on CircleCI develop

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## **Related issues**
## **Manual testing steps**
## **Screenshots/Recordings**
## **Pre-merge author checklist**
## **Pre-merge reviewer checklist**

app/scripts/lib/setupSentry.js

@@ -125,7 +125,7 @@ function getTracesSampleRate(sentryTarget) {
     // Report very frequently on develop branch, and never on other branches
     // (Unless you use a `flags = {"sentry": {"tracesSampleRate": x.xx}}` override)
     if (flags.circleci.branch === 'develop') {
-      return 0.03;
+      return 0.015;
     }
     return 0;
   }