publishers: correct XML element for boosttest xunit

The xUnit publisher (introduced by 2736e149) add a copy paste issue that
caused the 'boostest' type to use an XML element named
AUnitJunitHudsonTestType instead of BoostTestJunitHudsonTestType.

Closes-Bug: 1239121
Change-Id: I612075f5327025136d161dd60653a4f8edabb772
Merge "publishers: correct XML element for boosttest xunit"