[7.x] Correct field for rum page url (#76916) (#77153)

Author: shahzad31

x-pack/plugins/apm/common/__snapshots__/elasticsearch_fieldnames.test.ts.snap

@@ -95,7 +95,7 @@ export const POD_NAME = 'kubernetes.pod.name';
 export const CLIENT_GEO_COUNTRY_ISO_CODE = 'client.geo.country_iso_code';
 
 // RUM Labels
-export const TRANSACTION_URL = 'transaction.page.url';
+export const TRANSACTION_URL = 'url.full';
 export const CLIENT_GEO = 'client.geo';
 export const USER_AGENT_DEVICE = 'user_agent.device.name';
 export const USER_AGENT_OS = 'user_agent.os.name';