MDEV-25317 Assertion `scale <= precision' failed in decimal_bin_size And Assertion `scale >= 0 && precision > 0 && scale <= precision' failed in decimal_bin_size_inline/decimal_bin_size.

Precision should be kept below DECIMAL_MAX_SCALE for computations.
It can be bigger in Item_decimal. I'd fix this too but it changes the
existing behaviour so problemmatic to ix.