Remove project from grafana url placeholder

app/assets/javascripts/grafana_integration/components/grafana_integration.vue

@@ -13,7 +13,7 @@ export default {
     Icon,
   },
   data() {
-    return { placeholderUrl: 'https://my-url.grafana.net/my-dashboard' };
+    return { placeholderUrl: 'https://my-url.grafana.net/' };
   },
   computed: {
     ...mapState(['operationsSettingsEndpoint', 'grafanaToken', 'grafanaUrl', 'grafanaEnabled']),

spec/frontend/grafana_integration/components/__snapshots__/grafana_integration_spec.js.snap

@@ -51,7 +51,7 @@ exports[`grafana integration component default state to match the default snapsh
       >
         <glforminput-stub
           id="grafana-url"
-          placeholder="https://my-url.grafana.net/my-dashboard"
+          placeholder="https://my-url.grafana.net/"
           value="http://test.host"
         />
       </glformgroup-stub>