[CSV export] numeric fields being exported as strings

[blookot]

Kibana version: 7.6.2

Elasticsearch version: 7.6.2

Server OS version: Elastic Cloud

Browser version: Chrome latest version

Browser OS version: Windows 10

Describe the bug:

When using CSV export on a saved search you get numeric fields as strings in the csv file.

Steps to reproduce:

1. use ES monitoring index for instance
2. create a saved search with node_stats_jvm_mem_heap_max_in_bytes field for instance
3. export in CSV, you'll see this field is a string with commas...

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServices)

[elasticmachine]

Pinging @elastic/kibana-reporting-services (Team:Reporting Services)

[tsullivan]

Hi, can you check to see if the Advanced Settings has csv:quoteValues enabled?

[dokmic]

The issue was fixed as part of #67027, and the fix is available starting from 7.9. Previously, we were returning formatted values in the CSV export, which were containing commas in numeric values. Currently, we apply that formating only if it is explicitly set in the index patter field settings.