Cleanup: happily remove no-more-used PY_TRANSLATE RNA prop flag, and related code (just realized that flag value was wrong, probably own typo in a previous commit :/ ).

That "trick" was nice when introduced, but it became kind of a pita since we added translation contexts...

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54391 954f8c5b-7b00-dc11-b283-0030488c597c