display local time on note instead of UTC

[rrennick]

Fixes #2006

This PR changes the notes display date prop from date_created_gmt to
date_created.

Detailed test instructions:

• Update the date_created on an actionable note to the current time UTC
  update wp_wc_admin_notes set date_created = '2019-08-20 20:29:57' where note_id = 1234;
• Set you WP install to UTC-4 (America/New York)
• Open the notes panel
• The updated note will say 4 hours from now
• Switch to this PR
• The updated note will say Now

Changelog Note:

Fix: Date calculation on notes being double adjusted to UTC.

[psealock]

Thanks @rrennick This is testing well for me in a variety of scenarios.