fix(capacitor): Hide Capacitor from metrics. (#15621)

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Metrics will be supported once Capacitor SDK bumps JavaScript SDK to
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Author: lucas-zimerman

docs/platforms/javascript/common/metrics/index.mdx

@@ -8,6 +8,7 @@ beta: true
 notSupported:
   - javascript.deno
   - javascript.cordova
+  - javascript.capacitor
 ---
 
 With Sentry Metrics, you can send counters, gauges, distributions, and sets from your applications to Sentry. Once in Sentry, these metrics can be viewed alongside relevant errors, and searched using their individual attributes.