Previously, creating a declaration with Fir2IrCallableDeclarationsGenerator/
Fir2IrClassifiersGenerator didn't guarantee that this declaration will
be actually added to the list of parent class/file declarations, which
lead to situations when FIR2IR created some declarations in the air
(mostly fake-overrides)
This change allows to revert adding `WITH_STDLIB` directive
to tests which happened at `a9343aeb`.
Co-authored-by: Alexander Udalov <Alexander.Udalov@jetbrains.com>