The date/time formats are configured at form level irrespective of data list form or any other form you configure.
You can do it by extending the form properties. You can find OOTB form.get.properties under "<alfresco_installation_home>\tomcat\webapps\share\WEB-INF\classes\alfresco\site-webscripts\org\alfresco\components\form\form.get.properties" or check the source code here for taking the reference of all the properties.
You can try changing the properties related to time format and see if it works for you. I have not tried it though. However, i had extended date format specific properties to change the date format as i can recall and it worked.
These are the properties you would be looking to try and change:
## Format used for time entry in datetime picker, 'entry' format is used by date parsing code,
## 'display' format is shown to the user under time entry field
form.control.date-picker.display.time.format=HH:MM (24 Hour)
## Format used for date and time when form is in 'view' mode
form.control.date-picker.view.date.format=EEE dd MMM yyyy
form.control.date-picker.view.time.format=EEE dd MMM yyyy HH:mm:ss z
Here hh for 12 hour format and HH for 24 hour format.
Note that, this extension will change the time format across share, i.e. any property with dateTime data type on forms will display time format configured above. It is not specific to only data list.
(ACSCE, AWS SAA, Azure Admin)