Timezone bug in timefilter input

[berggren]

Describe the bug
When pasting a datetime string without timezone information and with a trailing space the timefilter form treats the string as local timezone and reformats to the wrong UTC time.

To Reproduce
Steps to reproduce the behavior:

1. Go to explore
2. Click on "+ timefilter"
3. Enter "2023-01-01 20:00:00 "
4. See the input change to "2023-01-01T18:00:00.000Z"

Expected behavior
The input should be "2023-01-01T20:00:00.000Z"

Desktop (please complete the following information):

• OS: macos
• Browser chrome
• Version latest