[FIX JENKINS-39034] /i18n/resourceBundle should be conform to the w3c standard...

[FIX JENKINS-39034] /i18n/resourceBundle should be conform to the w3c standard about locale negotiation (#2594)

* [parseCountry] Extract region/country and variant from the language parameter in case it is bigger then 2 letters. Add tests for both cases.

* [JENKINS-39034] remove debug system out

* [JENKINS-39034] Only if we have 5 or more character we want to get the country - prevent NPE

* [JENKINS-39034] use split since it is more general

* [JENKINS-39034] Only override country and variant if not already set

* [JENKINS-39034] better test cases to test whether the fallback and variant resolving work corret

* [JENKINS-39034] remove duplicate tests and better name existing ones