[fix]: Use scaled float for all numeric transaction.marks.* values.

[simitt]

Follow up on #708.

This PR intends to ensure that all values stored under transaction.marks.*.* are stored as scaled float.

Tested with:

POST apm-7.0.0-2018.12.21/_doc
{
  "transaction": {
    "marks": {
      "navigationTiming": { 
        "ab": 1,
        "bc": 1.345
      },
      "else": {
        "cd": 1.90,
        "de": 1
      }
    }
  }
}

leads to following mapping:

"marks" : {
                "dynamic" : "true",
                "properties" : {
                  "*" : {
                    "properties" : {
                      "*" : {
                        "type" : "object",
                        "dynamic" : "true"
                      }
                    }
                  },
                  "else" : {
                    "properties" : {
                      "cd" : {
                        "type" : "scaled_float",
                        "scaling_factor" : 1000000.0
                      },
                      "de" : {
                        "type" : "scaled_float",
                        "scaling_factor" : 1000000.0
                      }
                    }
                  },
                  "navigationTiming" : {
                    "properties" : {
                      "ab" : {
                        "type" : "scaled_float",
                        "scaling_factor" : 1000000.0
                      },
                      "bc" : {
                        "type" : "scaled_float",
                        "scaling_factor" : 1000000.0
                      }
                    }
                  }
                }
              },

Invalid payload:

POST apm-7.0.0-2018.12.21/_doc
{
  "transaction": {
    "marks": {
      "navigationTiming": { 
        "ab": 1,
        "bc": 1.345
      },
      "else": {
        "cd": 1.90,
        "de": 1,
        "ef": {
          "gh": 1.2
        }
      }
    }
  }
}

leads to:

{
  "error": {
    "root_cause": [
      {
        "type": "mapper_parsing_exception",
        "reason": "failed to parse field [transaction.marks.else.ef] of type [scaled_float]"
      }
    ],
    "type": "mapper_parsing_exception",
    "reason": "failed to parse field [transaction.marks.else.ef] of type [scaled_float]",
    "caused_by": {
      "type": "json_parse_exception",
      "reason": "Current token (START_OBJECT) not numeric, can not use numeric value accessors\n at [Source: org.elasticsearch.common.bytes.BytesReference$MarkSupportingStreamInputWrapper@1811506a; line: 11, column: 16]"
    }
  },
  "status": 400
}

cc @jahtalab and @vigneshshanmugam

@graphaelli maybe I am overlooking something here, but it seems to me that setting scaled floats on a wildcard works as expected now.

[graphaelli]

I'd be really glad to hear that someone added support for that. Looking back at #708 (comment) it does seem like it didn't used to work.

[simitt]

It still only ensures all number types are stored as scaled_floats, but as we don't allow anything else than numbers on the intake level, that should be fine.

[hmdhk]

Thanks @simitt! The structure looks correct, on the agent side we always set numbers for marks, so as you said it should not be a problem!

[simitt]

Also checked how this behaves when upgrading from an older version, where other marks have been indexed as long or float and couldn't see any issues with that.