Adapt Date/Time formatting tests to accommodate narrow non-breaking spaces

[snicoll]

Overview

We have a number of tests that assert that a converted time ends with specific content, such as "12:00:00 PM" (with a standard space instead of a narrow non-breaking space (NNBSP)).

In Java 20, the space between the time and PM was changed to an NNBSP, and the assertions fail for that reason only. We should find a way to make those tests more robust to that change.

And in Java 23, the support for using legacy locale data for Date/Time parsing and formatting was removed. In other words, the -Djava.locale.providers=COMPAT command-line argument is no longer supported.

This is required to run CI on Java 23 ea.

Related Issues

• Ensure compatibility with JDK 20 #30185
• Support lenient parsing for dates using AM/PM in conjunction with @DateTimeFormat #30649

[snicoll]

Oh dear, looks like we know this since last year already...

Duplicate of #30649

[snicoll]

reopening to focus only on tests here.