The default date format is not taken into account when using any other language than English and German

Steps to Reproduce

1. Change the user language or global language to e.g. Japanese;
2. In any issue, try to use any date picker field;
3. It will use "dd/MM/yy" in the Japanese interface.

Expected Results

JIRA should be able to use the same date format for all regions and languages.

Actual Results

Japanese interface is not using the system default date format.

• Issue affects all language except for English and German