Fix for Groovy5687Bug test case failing due to locale

Fixing Groovy5687Bug test case failing due to default locale producing 'em' as am/pm marker.

When having swedish as default locale Groovy5687Bug.groovy fails with

    Assertion failed:
    assert DateTimeUtils.convertMilitaryTimeToAmPm('20:30') == '8:30pm'
                         |                                  |
                         8:30em                             false

this pr fixes this and all 7215 tests pass