CSV report is getting generated in the actual machine timezone in stead of adhering to advanced settings timezone

[rashmivkulkarni]

Kibana version: 6.6.0 /master

Bug description: The timestamp on CSV reports being generated in a wrong timezone. To reproduce -
Here are the time zones:

• machine timezone: PST
• Kibana advanced settings timezone: UTC

The CSV report is generated in PST instead of UTC - Which I think is a bug .

Attached is the generated CSV.
Report.csv.txt

cc @aliciascott @legrego @calebchaney

[elasticmachine]

Pinging @elastic/kibana-app

[tsullivan]

looking into this now

[tsullivan]

I can repro with this test data:

PUT my_index
{
  "mappings": {
    "_doc": {
      "properties": {
        "date": {
          "type": "date" 
        },
        "name": {
          "type": "keyword" 
        }
      }
    }
  }
}

PUT my_index/_doc/1
{
  "date": "2019-01-01",
  "name": "Kaiden"
} 

PUT my_index/_doc/2
{
  "date": 1546300800001,
  "name": "Chance"
} 

PUT my_index/_doc/3
{
  "date": "2019-01-01T12:10:30Z",
  "name": "Grayson"
} 

GET my_index/_search
{
  "sort": { "date": "asc"} 
}

[tsullivan]

Relevant:
[1] elastic/elasticsearch#30831
[2] #27310

[tsullivan]

PR in the works: #29781