'var <- rep(0, n_years)' foll0wed with 'var <-' on another line

[CWWhitney]

We can streamline the script and remove some redundancies where we call this. For example:
PPcost_einkorn <- rep(0, n_years)
PPcost_einkorn <-
vv(crop_pp_cost, var_CV = var_cv, n_years) * Treeless_einkorn_yield

works the same as

PPcost_einkorn <-
vv(crop_pp_cost, var_CV = var_cv, n_years) * Treeless_einkorn_yield

The

PPcost_einkorn <- rep(0, n_years)

Just gets overwritten

https://github.com/PrajnaKARai/HofLebensbergFruitAF/blob/72082decb83b4576d06ac9572e2657e4bbb1202c/MixedFruitAFsystem.R#L174C1-L178C72