tests: userspace: exclude ucans32k1sic due to lack of MPU regions

This board have an NXP MPU with 8 configurable regions, of which five
of them are already used by the static MPU configuration. Many of
these tests are failing due to lack of MPU regions or free partition
slots available, even when HW stack protection is disabled when
building with userspace support.

Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>