ISTEXT() was used on non-text cells #2289

GIMS return either a number or NULL, but never a text for filter
values. Original formulas assumed it could return an empty string.
So we modify the formula to use better semantic with NOT(ISNUMBER())
Custom replacement branch of Sanitation is a summand itself #2289

It was previoulsy ignored and lead to signficantly lower results
for Flush and pour flush (eg: Cambodia, SES07)