New help center: date picker format not aligned with Jira settings

Summary

• When the date format is changed in Jira(https://<instance_name>.atlassian.net/secure/admin/AdvancedApplicationProperties.jspa), the date picker field in the "new help center" should conform to the settings defined in Jira
• Currently, when the date format has been changed e.g. dd.MM.yyy instead of the default d/MMM/yy format, the dates are either displayed incorrectly(dates in the future) or a false error message is thrown(dates in the past)
• This issue doesn't occur in the old help center
   

  Environment

• Jira Service Desk
• "new help center" enabled

Steps to Reproduce

1. Define the date format in Jira settings > System > General settings; Advanced Settings(https://<instance_name>.atlassian.net/secure/admin/AdvancedApplicationProperties.jspa). For demonstration purposes, we are using dd.MM.yyyy:
   
2. Add a date picker(type) field to the appropriate Request Type|https://confluence.atlassian.com/get-started-with-jira-service-desk/create-service-desk-request-types-917968307.html]
3. Ensure that the "new help center" is enabled. Navigate to Project Settings > Portal Settings > View and customize; under "Try the new help center. Click the toggle switch to the "on" position
4. Navigate to the help center and try to enter dates into the date picker

Expected Results

• Correct date displayed when entered using the expected date format
• Customer is allowed to enter dates as per the format defined in the "Advanced Jira Settings"

Actual Results

When setting a date in the past:

Old help center	New help center

When setting a date in the future:

Notes

• This issues only happen in the "new help center"
• In the example above, the "Use ISO8601 standard in Date Picker" setting is set to "Yes". The "Use ISO8601 standard in Date Picker" setting also has no effect on the date picker in the "new help center"; Jira settings > System > Look and feel(https://<instance_name>.atlassian.net/secure/admin/LookAndFeel!default.jspa)

• The date picker seems to work correctly when using the default d/MMM/yy format

Workaround

• Turn off the "new help center": Navigate to Project Settings > Portal Settings > View and customize; under "Try the new help center", put the toggle switch into the "off" position.  Please quote this bug ticket number in the feedback form.