fix: revert special handling of Indonesian locale [DHIS2-17522] (2.39)

[jbee]

Summary

JDK Locale has some build in conversions for language tags. These can evolve and thereby change with the JDK version. One such change presumably was causing issues for in vs. id language tag. In #16660 and #16623 an attempt was made to work around the Locale behaviour. While this worked for the code path looked at in the ticket this introduced a big issue. In order to work the locale was stored as String in the UI_LOCALE setting. This would cause class cast exceptions elsewhere when that value was cast to Locale. This was and is simply the contract of the setting that its value is an instance of Locale. As settings have the common denominator of Serializable this type issue could slip though the type checking. Also the settings service lacks validation that would make sure that the stored value is actually of the type specified with each setting key.

As we have to store the UI_LOCALE as a Locale instance but just using that class comes with the unwanted behaviour for the in vs id problem that problem simply cannot be addressed. This would require a complete revamp of large parts of the settings which s beyond the scope of the problem.

In addition to reverting the original fix this also fixes an issue found while testing in the settings controller where the content type needs to be specified explicitly to have jackson understand the target of the conversion.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
1 Accepted issue

Measures
0 Security Hotspots
0.0% Coverage on New Code
10.3% Duplication on New Code

See analysis details on SonarCloud