synchronize json schema specs (elastic#1372)

Co-authored-by: apmmachine <infra-root-apmmachine@elastic.co>

Author: apmmachine

tests/upstream/json-specs/metricset.json

@@ -129,6 +129,31 @@
  }
  }
  },
+ "service": {
+ "description": "Service holds selected information about the correlated service.",
+ "type": [
+ "null",
+ "object"
+ ],
+ "properties": {
+ "name": {
+ "description": "Name of the correlated service.",
+ "type": [
+ "null",
+ "string"
+ ],
+ "maxLength": 1024
+ },
+ "version": {
+ "description": "Version of the correlated service.",
+ "type": [
+ "null",
+ "string"
+ ],
+ "maxLength": 1024
+ }
+ }
+ },
  "span": {
  "description": "Span holds selected information about the correlated transaction.",
  "type": [