Remove getConfig() call from convertUSGS()

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Calling getConfig() for 'regionmapping' from read-functions

mrindustry/R/readUSGS.R

Line 265 in 2bf253b

iso3c = toolGetMapping(name = getConfig('regionmapping'),

is verboten, and will be disabled any time now. Like, probably next week.

On the upside, convertUSGS() is used exactly

> library(mrremind)
> library(madrat)
> 
> getDependencies('readUSGS', 'dout')
            func type    package                      call     hash
1     calcCement calc mrindustry   mrindustry:::calcCement 18eacd1e
2 calcHistorical calc   mrremind mrremind:::calcHistorical 95d0464b
> 
> getFunction('calcCement', where = .getNamespace('mrindustry')) |>
+     format() |>
+     grep('readSource.*USGS', x = _, value = TRUE)
[1] "    d_USGS_cement <- readSource(\"USGS\", \"cement\", convert = FALSE) %>% "
> 
> f <- getFunction('calcHistorical', where = .getNamespace('mrremind')) |>
+     format()
> 
> f[grep('readSource.*USGS', x = f) + 0:1]
[1] "    USGS_cement <- readSource(type = \"USGS\", subtype = \"cement\", "                
[2] "        convert = FALSE) %>% quitte::madrat_mule() %>% group_by(!!!syms(c(\"iso3c\", "

nowhere.
So we can just delete it.

Does anybody need madrat development practice, @JakobBD?