Kibana version:
6.3.2 - 8.0.0

Elasticsearch version:
6.3.2

Server OS version:
Ubuntu

Browser version:
Chrome Version 71.0.3578.98 (Official Build) (64-bit)

Browser OS version:
OSX

Describe the bug:
When explicitly setting dateFormat:tz in Advanced Settings it appears that monitoring is not adhering to that value but instead the local browser time zone.

Steps to reproduce:

1. Set UTC in advanced configuration (my local time is CST)
2. Setup monitoring and ship some data
3. Check discover uses UTC
4. Check monitoring tab -- mine shows the X axis as local browser time.

Expected behavior:

Screenshots (if relevant):

(Note: discover tab acknowledges UTC)