devel/kf5-kdoctools: add upstream fix for lang/kturtle

lang/kturtle was failing due to albanian customizations not being
availble in the used KDE Frameworks version in the quarterly branch.

From upstream [1]:

They were added in 2011 [2] but apparently never hooked up with the
build system.
Also remove the weird duplication of KDOCTOOLS_LANGUAGES_LIST. It
isn't needed and because the "set" invocation uses a variable
reference instead of the variable name it probably creates a variable
with the name "af" containing "bg ca cs da ...".

This commit allows building the Albanian documentation of kturtle,
which currently fails due some missing entities. As such it's a
stopgap measure, likely to be replaced with a dynamic language list.

[1] https://invent.kde.org/frameworks/kdoctools/-/commit/4121e38824b45068ee0f0aca9c7c8d38783a9f32
[2] 059121245d6d2b74287616d79416412680348ac0 in kdelibs.git