Fix categories with a namespace prefix in the cat name for CatWatch

Fix categories with a namespace prefix in the cat name for CatWatch

Title::newFromText will use the given namespace as default, but when
parsing a title with a namespace at the begin the method will not use
the default, instead used the namespace from the given text.
Use Title::makeTitle to create a title with always belongs to the given
namespace.

Bug: T119763
Change-Id: Ic96671e1c33c6572b07f0f859d97c85a7a15bd39