[explore][south tables] When copy data from 'view result' timestamp is not showing in correct format

[jinghua-qa]

When copy data from 'view result' timestamp is not showing in correct format

How to reproduce the bug

Use vehicle sales dataset

1. Go to explore
2. Query metric 'Sum(sales)
3. Click on the copy button in south tables to copy result
4. Paste the result and compare the timestamp column in data panel
5. See error

Expected results

timestamp column show same format as data panel

Actual results

timestamp column show different format as data panel

Screenshots

Environment

(please complete the following information):

• browser type and version:
• superset version: superset master
• python version: python --version
• node.js version: node -v
• any feature flags active:

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

Additional context

Add any other context about the problem here.

[junlincc]

one chart or all?